Strategic leadership and technological innovation: A comprehensive review and research agenda

Research Question/Issue: We review the literature on the relationship between strategic leadership and technological innovation. Research Findings/Insights: We identify the theoretical lenses that researchers apply when studying strategic leadership and innovation, most notably agency theory and upper echelons theory. We review the innovation constructs and measures that scholars employ, and we survey the links among strategic leaders' characteristics and technological innovation. Ultimately, we organize the literature into an integrative framework that provides a concise overview of the extant knowledge, and we outline an agenda for future research. Theoretical/Academic Implications: First, we offer scholars a discipline-spanning overview of the extant knowledge on the topic. Second, by integrating important aspects of corporate governance, such as the role of the board of directors, incentives for the chief executive officer or the top management team, and firm ownership, into the context of technological innovation, we highlight the vital role it plays in the realm of technological innovation. Third, we provide a useful guide for scholars and direct their work towards fruitful avenues for future research. Practitioner/Policy Implications: We offer insights for practitioners interested in better understanding the bidirectional relationship between strategic leadership and technological innovation. In particular, our framework and our detailed analysis of the impact of strategic leaders on technological innovation can guide shareholders and board members in matters related to board composition as well as top executive selection and compensation.

Scholars have conducted valuable reviews in the field of innovation, including reviews of literature on the role of leadership. However, the limited reach of these reviews has ramifications for the analytic, predictive, and normative potential of research in this domain. Three limitations are particularly noteworthy. First, several broad reviews of the innovation literature identify managerial characteristics as one of several antecedents of technological innovation (Ahuja, Lampert, & Tandon, 2008) or technological discontinuities (Eggers & Park, 2018), but they hardly discuss the paths of influence.
Second, some reviews offer outdated and incomplete overviews of the relevant characteristics of strategic leaders. For example, Crossan and Apaydin (2010) investigated the impact of the board and the TMT on innovation. However, that review is a decade old and only captures a small subset of the relevant characteristics of strategic leaders.
Third, some reviews only link certain strategic leaders with specific innovation outcomes. For example, Back and Bausch (2019) examined the impact of chief executive officer (CEO) leadership on various firm-level antecedents of product innovation, such as social capital. Yet they do not consider a substantial number of studies that directly link CEO characteristics to technological innovation more broadly, and they do not consider strategic leaders other than the CEO. As such, no comprehensive review on strategic leadership and technological innovation is available, making it difficult for scholars to build on previous findings and identify relevant research questions.
Our review fills this gap. We aim to answer four interrelated

| METHOD
To ensure a comprehensive account of the literature, we conducted a systematic review (e.g., David & Han, 2004;Rousseau, Manning, & Denyer, 2008). Given the multidisciplinary nature of the domain, we first identified 35 relevant peer-reviewed journals from different fields. These included the 30 outlets used in Wowak et al.'s (2017) recent review of incentives in strategic leadership. To specifically capture corporate-governance aspects, we also included a leading journal focused on that topic. In addition, owing to the focus of this review, we included two journals concerned with innovation, which two innovation scholars confirmed were the most important in the field.
Finally, we included two major journals dealing with family firms, as family firms are one of the most prevalent firm types (La Porta, Lopez-De-Silanes, & Shleifer, 1999;Lodh, Nandy, & Chen, 2014).
Moreover, family ownership and family involvement in strategic decision making substantially affect firms' technological innovation (De Massis, Frattini, & Lichtenthaler, 2013;Lodh, Nandy, & Chen, 2014). In fact, as De Massis et al. (2013, p. 10) noted, "there are strong theoretical reasons to believe that the antecedents and effects of technological innovation are different in family and nonfamily firms." Again, we validated our selection with two family business scholars. Table 1 provides an overview of the journals included in our review.
Using the above-mentioned definitions of strategic leadership and technological innovation as our conceptual anchors, we created a list of keywords. To validate our selection of keywords, we discussed them with management and innovation scholars and consulted scholars from economics and finance. These discussions led to the addition of a few keywords to our initial list. Table 2 shows the final list of keywords used in our literature search.
We set the review's starting point to 1984 to cover all literature published after Hambrick and Mason's (1984) seminal paper, which highlighted the importance of strategic leaders for organizational outcomes and laid the foundations for upper echelons theory. We then identified an initial sample of 937 articles published before the end of 2019 using the Web of Science database.
We read all articles' abstracts and, if necessary, their main texts and retained those articles that fulfilled two criteria. First, each article had to examine strategic leaders (i.e., boards of directors, CEOs, other TMT members, and/or business unit heads) (Finkelstein, Hambrick, & Cannella, 2009). Second, each article had to focus on technological innovation (Damanpour, 1987). We removed articles in which the hypotheses or propositions were not related to both criteria. Moreover, we removed articles dealing with young firms and start-ups owing to the specific context in which these firms and their strategic leaders operate (e.g., Park & Tzabbar, 2016).
Overall, we retained 158 articles and systematically coded each article for central theoretical and methodological aspects. For example, we examined the theoretical lens(es) that each study applied as well as the methodological approaches and the results. Table A1 in Data S1 summarizes the studies we reviewed.
In line with the growing importance of technological innovation for organizations (Tidd & Bessant, 2018), the number of studies on strategic leadership and technological innovation rose over time. As An analysis of the studies' research approaches and geographical focus reveals other interesting insights, which are summarized in Table 3. First, most studies employed a quantitative research approach, usually based on archival data or, to a lesser extent, surveys.
Few studies used qualitative research methods, such as case studies, or employed experimental or conceptual approaches. In addition, many of the empirical studies focused on the United States, followed by a focus on multicountry datasets. Little research investigated individual countries other than the United States, with China being a distant second. Technological change/novelty/search Technology Note. We use asterisks (*) at the end of a keyword to account for variations in this root word (e.g., our results include all words containing the root 'innovat', such as innovation, innovator, or innovative).

| AN INTEGRATIVE FRAMEWORK ON STRATEGIC LEADERS AND TECHNOLOGICAL INNOVATION
A framework that aggregates the findings from our analysis is shown in Figure 2. We employ a strategic leadership perspective, which assumes that strategic leaders' cognitive bases and values affect innovation through a filtering process (Finkelstein, Hambrick, & Cannella, 2009;Hambrick & Mason, 1984). By extension, we acknowledge that firm leaders may be affected by firm characteristics, and we also consider such relationships.
Our framework displays the main theoretical lenses used by scholars. Moreover, it includes the key individual-level and group-level characteristics of strategic leaders engaged with technological innovation. We distinguish between board and TMT characteristics, and we split the constructs into those focused on these groups as a whole and those focused on individual members of the board or TMT. Owing to the prominent role of the CEO in organizations (Finkelstein, Hambrick, & Cannella, 2009), we review CEO characteristics separately. We link strategic leaders' characteristics to the major innovation-related constructs. First, we consider innovation input, such as research and development (R&D) intensity (e.g., Cremers, Litov, & Sepe, 2017). Second, we consider innovation output, such as patents (e.g., Custódio, Ferreira, & Matos, 2019). Third, given the challenges of transforming innovation input into output (Duran, Kammerlander, van Essen, & Zellweger, 2016), we consider the relationship between strategic leaders' characteristics and the innovation process, such as product development (e.g., Swink, 2000). Fourth, we look at strategic leadership and aspects of the intraorganizational innovation context, such as a firm's innovation orientation (e.g., Carmeli & Halevi, 2009).
Finally, our framework depicts the consequences of the relationship between strategic leadership and technological innovation for firm performance and describes moderating environmental and organizational factors. All in all, we strive to provide a concise overview of the extant knowledge and to highlight gaps in that knowledge.  (Hambrick & Mason, 1984) is the most widely used theory (37 articles). Most scholars using this theory examine the impact of CEO and group-level TMT characteristics on innovation (e.g., Barker & Mueller, 2002;Talke, Salomo, & Kock, 2011). Few studies focus on the board or individual TMT members other than the CEO (Garms & Engelen, 2019;Kor, 2006;Shi, Pathak, Song, & Hoskisson, 2018). This is not surprising given the initial emphasis of upper echelons theory on CEO and group-level TMT characteristics (Carpenter, Geletkanycz, & Sanders, 2004 creative leadership and operational leadership is positively related to a firm's innovation quantity. Moreover, Gerstner et al. (2013) showed that narcissistic CEOs are more willing to adopt discontinuous technologies.

| Main theoretical lenses
Agency theory (Jensen & Meckling, 1976) is the second most frequently used theory (31 articles). In line with agency theory's focus on the relationship between principles and agents (Eisenhardt, 1989), several studies shed light on the role of board-level characteristics in interaction with CEO (e.g., Lim, 2015) or TMT characteristics (e.g., Kang & Zaheer, 2018;Kor, 2006). For example, Zona (2016) analyzed the interactive effect of the board's outsider ratio and CEO tenure on R&D intensity. Other articles focus on relationships between innovation and certain board characteristics, such as board composition (e.g., Osma, 2008;Robeson & O'Connor, 2013), or board compensation and ownership (e.g., Deutsch, 2007;Kang & Zaheer, 2018).
Some studies investigate individual CEO characteristics (e.g., Balkin, Markman, & Gomez-Mejia, 2000;Zahra, 2005). Consistent with agency theory's emphasis on the design of appropriate incentive structures (Eisenhardt, 1989), the majority of these studies analyze how innovation is related to CEO compensation and ownership (e.g., Fong, 2010). For example, Makri et al. (2006) found a positive relationship between citations of firm patents and CEO compensation.
The authors apply other theoretical lenses much less frequently.
Scholars occasionally employ other theoretical lenses, such as the attention-based view (Koryak, Lockett, Hayton, Nicolaou, & Mole, 2018;Maula, Keil, & Zahra, 2013) or resource-dependence theory (Datta & Guthrie, 1994;Wu, 2008). Kalyta (2009) combined findings from managerial hegemony and optimal contracting theory to deduce compensation transparency theory. The author found that CEOs with supplemental retirement plans contingent on firm performance reduce R&D investments as they approach retirement. H. Li et al. (2007) used procedural justice theory and found that a higher degree of perceived procedural justice in the TMT's decisions is positively related to the performance of newly developed products.

| Innovation-related constructs
As mentioned above, we distinguish among innovation input, output, and processes. In addition, we identify several constructs related to the intraorganizational context. We first introduce the innovationrelated constructs before reviewing the relationships between these constructs and strategic leaders' characteristics.
A few authors investigate the external adoption of technologies.
In that regard, most scholars use variables related to research alliances F I G U R E 3 Main theoretical lenses. CEO, chief executive officer; TMT, top management team that create opportunities for firms to obtain innovation input.
Whereas some scholars analyze the number of formed alliances (Eisenhardt & Schoonhoven, 1996;Howard, Withers, & Tihanyi, 2017) or whether companies would hypothetically form or did form an R&D alliance (Sullivan & Tang, 2013;Tyler & Steensma, 1998), Kang and Zaheer (2018) examined the network distance between research alliance partners (i.e., the length of the shortest path between the partners in an alliance before the actual formation of that alliance).
Other researchers analyze additional aspects of technology adoption.
Most studies that analyze the number of patents use them as a proxy for innovation quantity or innovation activities (e.g., Jung, Chow, & Wu, 2003;Makri & Scandura, 2010). Kaplan (2008a), for example, analyzed the degree to which firms invest in new technological fields by comparing the number of patents in those fields with the firms' total number of patents. All studies in our sample that rely on patent data count the number of granted patents instead of patent applications owing to data availability, but they use the patent application date to determine when the innovation activity took place (Wu, Levitas, & Priem, 2005).
As patent counts do not account for variations in the technological and economic impacts of different patents (Hall, Jaffe, & Trajtenberg, 2005), scholars often use patent citations to measure innovation output. First, scholars use patent citations as a supplementary proxy for innovation output that accounts for output quality (e.g., Chen, Podolski, Rhee, & Veeraraghavan, 2014;Sunder, Sunder, & Zhang, 2017). Second, some scholars conduct more nuanced analyses of innovation output through patent citations (e.g., Cremers, Litov, & Sepe, 2017;Faleye, Hoitash, & Hoitash, 2011). For instance, Cho and Kim (2017) identified patents with the largest number of forward citations and classify them as breakthrough innovations with high impacts in specific technological fields.
Other scholars analyze innovation efficiency. More specifically, they measure patent output relative to R&D investments (e.g., Bannò, 2016;Chemmanur, Kong, Krishnan, & Yu, 2019;Galasso & Simcoe, 2011) to evaluate the degree to which firms transform innovation input into output. Still other scholars analyze the firm's output elasticity, which is defined as changes in revenue resulting from changes in R&D (Cremers, Litov, & Sepe, 2017).

| The relationship between strategic leaders and technological innovation
Various studies illuminate the innovation-related effects of individualand group-level characteristics of the board, characteristics of the CEO, and individual-and group-level characteristics of the TMT.

| Individual-level board member characteristics
Relatively little research has focused on the impact of individual directors' characteristics on technological innovation. In fact, we identified research on only one situation in this regard-when the board's chairperson is an outside director, a case often referred to as "CEO nonduality" (e.g., Finkelstein & D'Aveni, 1994;Zona, 2016). The key idea in these studies is that outside board chairs can align the interests of management and shareholders to mitigate agency problems, which are particularly prevalent in the innovation context owing to the inherent risk and uncertainty. Kor (2006) (Lim, 2015) and family ownership (Chen & Hsu, 2009) on innovation outcomes. Balsam et al. (2016) studied the reverse relationship-how innovation affects strategic leaders. They find that R&D-intensive firms are more likely to have an outside board chair, and they argue that shareholders of such firms might prefer an outside chairperson to ensure oversight over management. Overall, Balsam et al.'s (2016) findings suggest that Kor's results should be treated with caution.

| Group-level board characteristics
More research has examined the board's group-level demographic characteristics in the context of technological innovation. Generally, this stream of research finds a positive relationship between gender and racial diversity and innovation outcomes, as such diversity might contribute novel perspectives and ideas to board discussions (Bernile, Bhagwat, & Yonker, 2018;Miller & Triana, 2009). Cook and Glass (2015) found that the positive association between board diversity and product innovation was particularly important in a sample of US firms "when a White CEO operates with a diverse board" (p. 117).
With regard to board members' prior experience, research finds that the innovation outcomes of work-related experience and education-related experience differ. Work experience in other firms and industries influences directors' decisions on complex strategic issues, including technological innovation. In this regard, firms show higher innovation input and output when they have a higher number of outside directors with work experience in patent-intensive firms (Balsmeier, Buchwald, & Stiebale, 2014) or with technical, researchrelated work experience (Dalziel, Gentry, & Bowerman, 2011;Haneda & Ito, 2018). Dalziel et al. (2011) showed that directors' entrepreneurial finance experience is negatively related to R&D investments-such experience might lead directors to focus on cost-effective research practices. The implications of educational experience are less clear. Whereas an elite education among directors is positively linked to innovation input, outside directors with a doctoral-level education, which should equip them with research-related skills, is surprisingly negatively related to innovation input (Dalziel, Gentry, & Bowerman, 2011). The same authors find no link between inside directors' doctoral degrees or entrepreneurial finance experience and R&D investments-stressing the need to distinguish between inside and outside directors.
A considerable body of work studies the effects of board composition and structure on technological innovation. Most studies investigate the impact of board independence on innovation outcomes by analyzing the ratio of outside directors to inside directors. In his metaanalysis, Y. Deutsch (2005) found a negative relationship between this ratio and innovation input. Notably, these findings contradict traditional agency theory, which highlights the importance of outside directors in reducing managers' reluctance to invest in risky, long-term innovation activities (David, Hitt, & Gimeno, 2001;Jensen & Meckling, 1976). One explanation might be that outside directors prefer external innovation acquisition because they have limited knowledge of internal R&D processes (Hoskisson, Hitt, Johnson, & Grossman, 2002). Moreover, Zona (2016) provided evidence that the negative relationship between the outsider ratio and innovation input might be contingent on CEO tenure, as he observes positive effects at later stages of CEO tenure. Relatedly, Osma (2008)  Board incentives have been studied only as they relate to stock ownership. First, studies indicate that board incentives can help increase the board's monitoring activities and, thereby, counter CEOs' risk aversion. 1 In particular, higher proportions of stock ownership by outside directors seem to curb the tendency of CEOs with more stock ownership to reduce R&D investments (Lim, 2015). Moreover, higher values of outside directors' stock options intensify the tendency of firms to increase R&D investments if they experience a decline in returns on assets (Lim & McCann, 2014 (2019) showed that both industry diversity in board ties and board interlocks with R&D-intensive firms increase the likelihood that firms engage in technological exploration. However, M. Li also found that the ratio of interlocks among directors with output functional experience is negatively associated with technological exploration, suggesting that interlocks among directors with this experience might be less important for technological innovation. Third, some ties hinder innovation. As Rose et al. (2014) showed, this seems to be the case for directors' intraorganizational friendship ties with the CEO, which are positively related to reductions in innovation investments aimed at providing short-term benefits to the CEO. Noticeably, this effect increases with the disclosure of such ties (Rose, Rose, Norman, & Mazza, 2014), highlighting the reputational effects of social relationships in firm governance.

| Individual-level CEO characteristics
A large body of research analyzes CEO characteristics in the context of innovation. Several studies investigate demographic characteristics as proxies for CEOs' cognitive frames (Hambrick, 2007). In this regard, various scholars find detrimental effects of age and tenure on CEOs' risk appetite, ability to process new information and, consequently, innovation activities. The longer a CEO is in office, the less that CEO is willing to invest in technological innovation-CEOs with longer tenures are more committed to established paradigms, and they tend to emphasize stability over technological change (Barker & Mueller, 2002;Zahra, 2005). Cheng (2004) demonstrated that compensation committees aim to alleviate this career-horizon problem by more closely linking R&D spending to compensation for older CEOs.
Moreover, high CEO age and a limited career horizon are associated with both reduced innovation input and output, as older CEOs might be less inclined to embrace new ideas and organizational changes (Barker & Mueller, 2002;Heyden, Reimer, & van Doorn, 2017;Kalyta, 2009). These findings also suggest that the reduced investments in R&D by older and longer tenured CEOs are not an indicator of greater innovation efficiency but rather a reflection of the preference of those CEOs to engage in short-term investments. In support of this argument, Cho and Kim (2017) found that the reduction in R&D investments mediates the negative relationship between CEO tenure and innovation output.
Work and educational experience are also related to CEOs' decision making regarding innovation (Barker & Mueller, 2002). Work experience in output functions that are characterized by an emphasis on business growth through the development of new products or new markets seems to lead CEOs to favor innovation strategies and is, consequently, associated with increased R&D spending. With regard to educational experience, there is a positive relationship between the CEO's number of science or engineering degrees and R&D expenditure, whereas the overall education level and number of business degrees have no significant effects as long as the CEO holds a college degree. However, this relationship might be driven by reverse causality, as Datta and Guthrie (1994) found that R&D-intensive firms are more likely to select CEOs with technical experience and a higher level of education.
Moreover, studies indicate a significant impact of CEO personality on innovation outcomes. Interestingly, although not surprising given the potentially glamorous but risky nature of technological innovation, firms' technological innovation outcomes seem to be a function of CEO personality traits related to risk seeking, a sense of superiority, and a desire for attention or acclaim, that is, sensation-seeking (Sunder, Sunder, & Zhang, 2017), overconfidence (Galasso & Simcoe, 2011;Hirshleifer, Low, & Teoh, 2012), hubris (Tang, Li, & Yang, 2015), and narcissism (Gerstner, König, Enders, & Hambrick, 2013), the latter also in paradoxical combination with humility (Zhang, Ou, Tsui, & Wang, 2017). Apparently, innovation requires narcissistic tendencies, which allow a CEO to derive utility from attention and to be less hesitant to invest despite unfavorable odds and substantial resource rigidity in organizations (Gerstner, König, Enders, & Hambrick, 2013;Gilbert, 2005). Furthermore, H. Zhang et al. (2017) found that CEOs' socialized charisma (i.e., their ability to inspire employees and to ensure support for novel routines and practices) mediates the positive interaction effect of high degrees of humility and narcissism on firms' innovation orientation.
Scholars have also examined the cognitive processes through which CEOs attend to and perceive their environment. First, studies show that CEO attention to specific technologies or productdevelopment processes affects related innovation outcomes (Calantone, Vickery, & Dröge, 1995;Eggers & Kaplan, 2009 Lefebvre et al. (1997) showed that perceived environmental dynamism increases the positive effects of a firm's technology policy (i.e., the degree to which a firm pursues technological changes and recruits relevant human resources) on innovation outcomes, whereas higher perceived hostility has negative effects on such policies, likely because it reduces investments with long payoff horizons.
The CEO's leadership style also influences technological innovation outcomes. The most studied leadership style in this context is transformational leadership, which positively affects innovation outcomes (Elenkov & Manev, 2005;Jung, Chow, & Wu, 2003;Jung, Wu, & Chow, 2008). This is not surprising given that the key elements of transformational leadership-charisma, idealized influence, and intellectual stimulation-enable leaders to elicit commitment from subordinates and drive employees' creativity (Jung, Wu, & Chow, 2008;Oldham & Cummings, 1996). Various organizational and environmental characteristics strengthen the relationship between transformational leadership and innovation outcomes, including an organizational climate of support for innovation, lower centralization and formalization within the organization, and higher degrees of competition and environmental uncertainty (Jung, Wu, & Chow, 2008 Other research explores the differences between transformational and transactional leadership, where the latter is characterized by a focus on clearly defined goal/reward systems for subordinates (Jansen, Vera, & Crossan, 2009). Elenkov and Manev (2005) identified generally positive effects of both leadership styles on organizational innovation. Jansen et al. (2009) found that transformational leadership positively affects exploratory innovation, whereas transactional leadership reduces flexibility and creativity and, thus, engenders exploitative innovation.
Research concerning other aspects of the relationship between CEO leadership styles and innovation is more limited. Elenkov and Manev (2005) found that laissez-faire leadership is negatively associated with organizational innovation, whereas they find no effects of active or passive management by exception. Makri and Scandura (2010) showed a significant positive interactive effect of creative and operational leadership on innovation quantity in high-tech firms, and they demonstrate that the highest levels of innovation quantity are achieved when both leadership dimensions are high. They find no effect on innovation quality and that only creative leadership (not operational leadership) is positively related to the use of science in innovation.
Various studies analyze the relationship between CEO incentives and innovation outcomes. Many of these studies focus on CEO compensation and argue that firms reward CEOs for risky, long-term investments in innovation. For example, studies find that innovation outcomes are positively associated with total CEO compensation (Makri, Lane, & Gomez-Mejia, 2006) and long-term option compensation (Baranchuk, Kieschnick, & Moussawi, 2014;Cheng, 2004). Other studies account for specific requirements in research-intensive industries and find a positive link between innovation input and output and short-term CEO compensation (Balkin, Markman, & Gomez-Mejia, 2000). In exploring the reverse relationship, Fong (2010) found that relatively underpaid CEOs in R&D-intensive industries are associated with higher R&D spending, whereas lower innovation input is evident when CEOs are underpaid in less R&D-intensive industries.
The underlying argument is that CEO compensation and R&D investments are better aligned in R&D-intensive industries. Research investigating broader cross-industry samples suggests nuanced effects of different compensation components on innovation outcomes.
Whereas compensation-based risk incentives are positively associated with innovation output (Mao & Zhang, 2018), large CEO inside debt holdings (Cassell, Huang, Sanchez, & Stuart, 2012) and deferred compensation and pension benefits (Kalyta, 2009) can reduce risk-seeking behavior and, in turn, diminish innovation input.
Several scholars analyze CEO stock ownership or stock options. On the one hand, there is a positive relationship between CEOs' general firm ownership and innovation outcomes (Barker & Mueller, 2002;Gedajlovic, Cao, & Zhang, 2012). On the other hand, higher values of stocks and options to be exercised in the short term (Edmans, Fang, & Lewellen, 2017) and increasing values of restricted stock (Lim, 2015) are negatively associated with R&D intensity. Some scholars include additional characteristics of the focal firm or its strategic leaders in their analyses. For example, Lim (2015) found that increased board vigilance due to a higher proportion of outside directors with more  authors demonstrate that CTOs' expert power, which originates from their technical expertise, is negatively related to innovation outcomes, and they suggest that CTOs high in expert power might be more aware of innovation-inherent risks.

| Group-level TMT characteristics
More research examines the TMT as a group in the context of technological innovation. Some of these studies investigate the TMTs' demographic characteristics. Although Bantel and Jackson (1989) did not find a significant direct effect of TMT age on innovation adoption, higher mean TMT age can aggravate the negative effect of a CEO's short career horizon on R&D intensity (Heyden, Reimer, & van Doorn, 2017). Relatedly, and similar to the findings regarding CEO tenure, a negative link exists between longer TMT tenure and R&D intensity (Kor, 2006). On the other hand, the benefits of knowledge derived from a longer tenure might outweigh inertial effects in hightech industries. For instance, Srivastava and Lee (2005)  With regard to the prior work experience of TMT members, when the TMT is experienced in specific topics or industries, it generally has a stronger focus on innovation activities related to those topics or industries (e.g., Hoffman & Hegarty, 1993;Somaya, Williamson, & Zhang, 2007;Urbig, Bürger, Patzelt, & Schweizer, 2013). For example, Tyler and Steensma (1998) found a positive relationship between the technical work experience of TMT members and their assessments of potential research alliances. Kor (2006) found a positive relationship between shared experiences among TMT members and technological innovation. In addition, heterogeneity in TMT members' functional backgrounds moderates the relationship between the board's outsider ratio and the firm's R&D intensity-for higher levels of TMT functional heterogeneity, the board's outsider ratio is increasingly negatively related to R&D intensity, whereas there is an increasingly positive relationship for lower levels of heterogeneity (Kor, 2006).
This research generally finds positive links between such types of diversity and innovation outcomes. However, Lyngsie and Foss (2017) cautioned that the positive association between a higher share of female top managers and innovation outcomes only occurs above a certain threshold, whereas the initial addition of female TMT members is even negatively associated with innovation outcomes.
Studies investigating TMT composition and structure mainly focus on the impact of TMT size on decision-making speed and processes (West & Anderson, 1996). A larger TMT is positively linked to alliance formation, as it is more likely to have the required resources, such as connections to potential partners (Eisenhardt & Schoonhoven, 1996).
In addition, firms with larger TMTs are more likely to be the first to introduce new products in an industry (Srivastava & Lee, 2005).
Some studies examine TMT composition and structure in the context of family firms. Matzler et al. (2015) showed that the number of family members in the TMT can positively affect innovation input and output. Notably, Vandekerkhof et al. (2015) demonstrated that a higher degree of firm innovation increases the need for the expertise of nonfamily TMT members. However, for firms with high levels of socioemotional wealth and thus a focus on family-related objectives, they find that the degree of innovation has no impact on the appointment of nonfamily TMT members. Moreover, Kraiczy et al. (2015) found a positive moderating effect of TMT family members' closeness to the first or founding generation on the relationship between the CEO's risk-taking propensity and product innovation.
Beyond demographic variables and TMT composition, research is increasingly focused on collaboration and behavior within the TMT in the context of technological innovation. This literature highlights the importance of cooperation within the TMT for managing complex innovation processes (Chen, Tjosvold, & Liu, 2006). In that regard, Furthermore, in line with the findings for board and CEO incentives, TMT compensation can compel managers to incorporate longterm considerations, like innovation, into their decision making. In that regard, higher total annual TMT compensation is positively related to firms' R&D intensity (Zhang, Chen, & Feng, 2014). In addition, the value of TMTs' exercisable stock options is positively related to firms' R&D spending, as managers might anticipate a positive reaction of investors to increased R&D investments (Souder & Bromiley, 2017).
In contrast, short-term performance incentives are negatively associated with R&D intensity (Hoskisson, Hitt, & Hill, 1993). However, studies investigating the reverse relationship highlight the importance of considering potential endogeneity, as higher R&D intensity is related to an increased duration of executive compensation, that is, a longer average vesting period of the TMT's compensation components (Gopalan, Milbourn, Song, & Thakor, 2014), and higher values of firm patents are associated with higher average TMT compensation (Frydman & Papanikolaou, 2018).
Finally, some research investigates whether TMT network ties provide executives with valuable information and resources in the innovation context. This research suggests, similar to that on CEO social capital, that substantial managerial ties are beneficial for innovation outcomes (Heavey, Simsek, & Fox, 2015;Kemper, Schilke, & Brettel, 2013). In a meta-analysis, Kraft and Bausch (2018) found that cohesive managerial networks (i.e., small networks with strong ties) are more beneficial for innovation in environments with weak political, regulatory, and financial institutions, whereas diverse networks stimulate innovation in more stable environments.

| Major contextual moderating factors
The literature review shows that the relationship between strategic leadership and technological innovation also depends on contextual factors. In this regard, we distinguish between environmental and organizational factors (Damanpour & Aravind, 2006).

| Environmental factors
Most studies considering contextual factors analyze environmental factors beyond the organization's boundaries. Some scholars analyze the sociocultural context-with mixed results. Those studies that consider the moderating impact of the firm location do not find a significant influence on the relationships between the TMT's functional role (Hegarty & Hoffmann, 1990), the TMT's experience (Hoffman & Hegarty, 1993), or its leadership behavior (Elenkov, Judge, & Wright, 2005) and innovation outcomes. In contrast, Hofstede's cultural dimensions do moderate the impact of TMT leadership style on innovation (Elenkov & Manev, 2005 Moreover, in dynamic environments, shorter CEO tenure (Wu, Levitas, & Priem, 2005) and higher CEO focus on the present and the future (Nadkarni & Chen, 2014) are beneficial for innovation outcomes.
A small number of studies investigate the moderating effects of other environmental factors. Some research considers industry-level characteristics, such as R&D intensity (Fong, 2010) or secrecy regarding innovation activities (Erkens, 2011). For instance, Erkens (2011) found a positive relationship between firms' R&D intensity and TMTs' unvested stock holdings. This relationship is more pronounced in industries with a lower propensity to use patents to protect innovation.

| Organizational factors
Organizational characteristics also influence the relationship between strategic leaders and technological innovation. In that regard, the CEO's focus on technologies might compensate for a lack of organizational experience with such technologies (Kaplan, 2008a). Furthermore, firm experience with technological alliances seems to accentuate top executives' willingness to engage in such alliances (Tyler & Steensma, 1998). With respect to organizational gender proportions, Lyngsie and Foss (2017)

| The impact of technological innovation on performance
Some studies investigate not only the impact of strategic leadership characteristics on technological innovation but also downstream performance effects. We distinguish between innovation-and firm-related performance measures.

| Innovation-related performance measures
Several studies investigate the financial performance of innovations using such measures as contributions to profitability, market share, or sales (e.g., Carson, Wu, & Moore, 2012;Li, Bingham, & Umphress, 2007;Wu, 2008). For example, Cummings and Knott (2018) found that outside CEO succession is negatively related to the firm's ability to generate sales through increased R&D investments, indicating a need for technical expertise and knowledge of internal processes to ensure the successful management of R&D investments. A single study investigates the capital market's reaction to failures in new product development and finds that managerial experience reduces negative market reactions to such failures (Urbig, Bürger, Patzelt, & Schweizer, 2013).

| Firm-related performance measures
Other scholars investigate whether the relationship between strategic leaders and innovation extends to overall firm performance. Several studies find that the positive effects of strategic leaders' characteristics on technological innovation lead to increased firm profitability (e.g., Calantone, Vickery, & Dröge, 1995;Lefebvre, Mason, & Lefebvre, 1997;Miller & Triana, 2009 (Biddle, 1986). Scholars could build on Georgakakis et al. to analyze how interactions between the CEO and individual functional executives involved in the innovation process affect innovation outcomes. Moreover, scholars could build on research that criticizes that agency theory might not sufficiently account for the socially situated context in which strategic leaders interact (Westphal & Zajac, 2013).

| Theoretical lenses
Along those lines, Luciano et al. (2020) recently proposed a novel perspective on interactions between the TMT and the board-the "strategic leadership system"-which highlights the common goals of the TMT and the board while acknowledging their specific responsibilities.
We see great promise in research that adopts a system view of strategic leadership and investigates how the exchange and utilization of experiences and knowledge within and between the board and the TMT contribute to technological innovation.
Some studies already use further well-established theories, such as the resource-based view (e.g., Kemper, Schilke, & Brettel, 2013;Kleinschmidt, Brentani, & Salomo, 2007) or leadership theory (Elenkov, Judge, & Wright, 2005;Osborn & Marion, 2009), to study the link between strategic leadership and innovation. However, scholars could fruitfully draw from a wider variety of alternative theoretical perspectives that have thus far only been sparsely applied. As technological innovation requires shifts in organizational routines and cognitive schemas (König, Graf-Vlachy, & Schöberl, 2020;Tripsas & Gavetti, 2000), it creates potential for conflict within the group of strategic leaders (Kammerlander, König, & Richards, 2018). Therefore, scholars could build on the theory of cooperation and competition (Deutsch, 1973) to study the role of conflicts and conflict management among TMT and board members in the context of technological innovation (Chen, Liu, & Tjosvold, 2005). Compensation transparency theory (Kalyta, 2009)  ing on social identity theory (Turner & Tajfel, 1986). Higher degrees of organizational identification among executives may exacerbate inertia, but it might also make executives more motivated to commit to long-term goals and, in turn, engage in organizational innovation activities.
Finally, several relevant theoretical lenses have not yet been used to examine the relationship between strategic leadership and technological innovation. First, this field of study has yet to fully make the "linguistic turn" (Vaara, 2010) that other streams in management studies have made-in other words, a shift towards viewing leadership as emerging through the management of the meaning of organizational events (Clifton, 2012;Gioia & Chittipeddi, 1991) and, in turn, towards the analysis of texts and discursive practices. For example, scholars could investigate how the rhetoric of strategic leaders contributes to sensemaking in organizations (Maitlis & Christianson, 2014) that face technological discontinuities, how strategic leaders legitimize the related organizational changes (Vaara & Tienari, 2008), and how strategic leaders are able to "construct" organizational adaptations to technological change in a positive way (Kaplan, 2008b). Alternatively, discursive approaches could be combined with findings from impression-management research (e.g., Davidson, Jiraporn, Kim, & Nemec, 2004;Graffin, Carpenter, & Boivie, 2011) to study how strategic leaders attempt to satisfy the expectations of internal and external audiences in times of technological change.

| The role of the board of directors in technological innovation
We identify considerable gaps in our knowledge of the board's role in innovation, which are particularly important given that research recognizes the general impact of boards on firm strategy (Carpenter, Geletkanycz, & Sanders, 2004;Pugliese et al., 2009). Moreover, it is impossible for scholars to generalize findings from extant research on the relationship between the CEO and/or the TMT, and technological innovation to boards, as boards' roles, responsibilities, and agency differ systematically from those of CEOs and other executives (Finkelstein, Hambrick, & Cannella, 2009).
Therefore, we encourage scholars to include boundary conditions of board activities in their research models. As discussed above, most studies on boards in the context of innovation use easily observable characteristics of board composition as proxies for board power, which drives boards' monitoring intensity (Kor, 2006)

| Consequences of technological innovation for strategic leaders
Innovation outcomes might substantially influence strategic leadership, for instance, firms' selection of executives (e.g., Shi, Pathak, Song, & Hoskisson, 2018), CEO nonduality (Balsam, Puthenpurackal, & Upadhyay, 2016), and executive compensation (e.g., Erkens, 2011). In this vein, we see two key avenues for future research on the consequences of firm innovation for strategic leadership. First, additional research could study the innovation-related antecedents of board and TMT composition. For example, scholars could study how and why CEO nonduality and the board's outsider ratio are a function of innovation. In this regard, Y. Deutsch (2005) suggested that the negative impact of the board's outsider ratio on R&D investments might be explained by reverse causality (i.e., by the desire for appropriate board vigilance if the CEO shuns R&D investments). Overall, we suggest that research on the innovation-related determinants of board and TMT composition should also consider the environmental and organizational factors from our framework as well as CEO characteristics (Balsam, Puthenpurackal, & Upadhyay, 2016;Zona, 2016) as potential moderators.
Second, scholars should study the effects of firm innovativeness on the cognitive processes and behaviors of strategic leaders. For example, scholars could study whether firm innovation affects strategic leaders' attention to and perceptions of certain issues (Ocasio, 1997) or could investigate the influence of innovation on the ways in which strategic leaders engage with each other or their employees. In answering such questions, scholars can build on research on managerial and board cognition (Kaplan, 2011;Rindova, 1999) and move beyond studies that merely compare the relationship between strategic leaders' characteristics and innovation in high-tech and low-tech industries (e.g., Srivastava & Lee, 2005).

| Research settings
Scholars might also use novel research settings to uncover new facets of the relationship between strategic leaders and innovation. Most of the studies reviewed here focus on US firms-few consider samples from other countries (e.g., Barney, Foss, & Lyngsie, 2018;Osma, 2008;Wu, 2008) or multinational samples (e.g., Cheng, 2004;Eggers & Kaplan, 2009;Elenkov, Judge, & Wright, 2005). However, cross-contextual differences (e.g., in cultural and legal aspects) are likely to affect the relationship between strategic leadership and innovation. In fact, local corporate-governance regimes differ substantially in ways that affect boards' discretion and legal obligations (Jungmann, 2006). Scholars might also investigate how directors' affiliations with educational institutions or other organizations affect innovation outcomes across countries owing to a differential influence of such affiliations on director status (Johnson, Schnatterly, Bolton, & Tuggle, 2011).
Moreover, most researchers study multi-industry samples of large, publicly listed firms. Although some find systematic differences in relationships between strategic leaders and innovation when comparing low-and high-tech industries (Srivastava & Lee, 2005), scholars could investigate other aspects of the industry context. For example, the effects of educational background or diversity among strategic leaders might differ between environments that diverge in technology or capital intensity, as they require different skills and capabilities.
Second, we contend that R&D-based and patent-based measures are still useful for improving our understanding of firms' innovation activities (Hagedoorn & Cloodt, 2003). Nevertheless, we call for greater statistical care with regard to R&D-based measures. The majority of scholars analyze standardized R&D investments (e.g., Heyden, Reimer, & van Doorn, 2017;Kor, 2006). However, using ratios as dependent or independent variables might result in inaccurate parameter estimates (Certo, Busenbark, Kalm, & LePine, 2020). Therefore, we suggest that scholars use unscaled R&D investments and control for the scaling factors when measuring innovation input.
With regard to patent-based measures, it likely makes sense to use citation-based measures of innovation output, at least in addition to simple patent counts (Hall, Jaffe, & Trajtenberg, 2005;Trajtenberg, 1990). Scholars should consider several aspects to ensure empirical validity and allow for comparisons across studies. Some studies include self-citations (e.g., Hirshleifer, Low, & Teoh, 2012), whereas others explicitly exclude such citations (e.g., Faleye, Kovacs, & Venkateswaran, 2014). As Sunder et al. (2017) pointed out, there might be systematic differences among firms that do or do not cite their own patents. Therefore, we suggest that scholars analyze patent citations both ways. In addition, researchers must address the data-truncation problem, which occurs because newer patents are likely to have fewer forward citations than older patents (Hall, Jaffe, & Trajtenberg, 2005). Moreover, researchers must account for differences across technology fields and industries with regard to the propensity to patent (Lerner & Seru, 2017). Most studies in our sample use Hall et al.'s (2001Hall et al.'s ( , 2005 adjustment approach (e.g., Custódio, Ferreira, & Matos, 2019;Faleye, Hoitash, & Hoitash, 2011). However, Lerner and Seru (2017) demonstrated that this approach can be problematic. They propose an adapted method that uses patents of publicly traded firms instead of the entire population of patents to adjust for truncation, and they show that this method alleviates at least some of the problems. They also provide a comprehensive checklist for researchers planning to analyze patent data.
Notably, patent-based innovation measures have moved beyond simply counting citations and patent grants (Savage, Li, Turner, Hatfield, & Cardinal, 2020). Several promising approaches may help link firms' technological innovations to strategic leadership characteristics. One possibility is to make use of text-mining techniques by, for instance, comparing patents or patent portfolios.
Analyses of textual similarity between patents can be used to track knowledge flows and knowledge spillovers (Arts, Cassiman, & Gomez, 2018;. Other options are to measure the novelty of innovations using semantic analyses of patents (Gerken & Moehrle, 2012) or to examine the inventors listed in the firms' patents, for example, to measure human capital quality based on the citations their patents attract (Byun, Oh, & Xia, 2020) or to analyze inventor mobility between organizations (Melero, Palomeras, & Wehrheim, 2020). Finally, scholars could further investigate the circumstances under which firms patent more novel innovations by analyzing the technology classes of patents (Balsmeier, Fleming, & Manso, 2017;Cho & Kim, 2017) or the degree to which firms cite scientific papers in their patents (Makri & Scandura, 2010).
Third, scholars can investigate aspects besides innovation input and output. Few studies examine the relationship between strategic leaders and innovation processes (e.g., Kemper, Schilke, & Brettel, 2013;Kleinschmidt, Brentani, & Salomo, 2007;Swink, 2000), and we have a limited understanding of the factors that allow firms to successfully transform innovation input into output (Duran, Kammerlander, van Essen, & Zellweger, 2016). Future studies could develop measures that will enhance our understanding of how strategic leaders affect innovation processes. With respect to the intraorganizational innovation context, studies to date have merely investigated the ways in which strategic leadership characteristics affect the TMT's influence on innovation (e.g., Elenkov, Judge, & Wright, 2005;Hoffman & Hegarty, 1993). Scholars could extend this logic to the board and analyze the link between specific board characteristics and the board's effect on innovation outcomes.

| Other methodological issues
Rich and promising avenues for future research also arise from other methodological issues, especially endogeneity and mediation analyses.

| Endogeneity
Accounting for endogeneity in strategic leadership research is "essential for gaining a grasp of the causal mechanisms that lie behind empirical associations" (Hambrick, 2007, p. 338). Aside from measurement error and simultaneity, the key sources of endogeneity in strategic leadership research are omitted variables (Bascle, 2008). In particular, TMT and board member selection are unlikely to be exogenous. The attractiveness of a firm to a strategic leader and the selection of strategic leaders are affected by firm characteristics and prior firm decisions (R. B. Adams, Hermalin, & Weisbach, 2010;Hambrick, 2007). Therefore, any relationship between strategic leadership characteristics and innovation outcomes might be caused by the same hard-to-observe factors that determine board and TMT composition.
Owing to the importance of endogeneity for strategic leadership research, we analyzed how the research in our sample addressed this issue. We built on the main sources of endogeneity outlined by Antonakis et al. (2010) to derive keywords referring to endogeneity. 2 We then read the method and results sections of all articles that contained at least one of these keywords. Figure 4 shows the main results.
The figure highlights the number of papers that methodologically address endogeneity concerns, name endogeneity as a potential limitation when interpreting the results, or do not explicitly address the issue. As illustrated, a number of studies in our sample, especially the earlier ones, do not explicitly account for endogeneity (e.g., Calantone, Vickery, & Dröge, 1995;Hoffman & Hegarty, 1993).
We also found that the quantitative methods used to address endogeneity have evolved over time. Whereas earlier studies often used simple approaches, such as lagging variables or conducting additional subgroup analyses as indicators for causal relationships (e.g., Barker & Mueller, 2002;Deutsch, 2007) We strongly advise scholars to use appropriate methods to address endogeneity. Research designs should be constructed to avoid endogeneity from the outset. For instance, longitudinal research designs may be helpful when using archival data F I G U R E 4 Reference to endogeneity as a methodological concern over time (Hamilton & Nickerson, 2003), and key variables should be mea-

| Mediation analysis
Our results show a pressing need to better understand the processes that mediate strategic leadership and innovation outcomes-the proverbial "black box" of strategic leadership research (Lawrence, 1997).
In fact, the extant research rarely includes mediation analyses of mechanisms involving the CEO (e.g., Chen, Tang, Jin, Xie, & Li, 2014) or the TMT (e.g., Ou, Waldman, & Peterson, 2018), and most studies on boards to date essentially only analyze the relationship between board composition and technological innovation. Therefore, especially regarding board research, a better understanding of behavioral or collaboration-related variables as well as board processes and dynamics is desirable. For example, future research could build on the initial qualitative research on boards in the context of innovation (Hoppmann, Naegele, & Girod, 2019;Morais, Kakabadse, & Kakabadse, 2019) to deduce potentially relevant mediating factors.

| Current trends in innovation research
Finally, several innovation topics appear relevant in relation to strategic leadership. First, digital technological innovation is reshaping entire industries, economies, and societies (Bankewitz, Aberg, & Teuchert, 2016;Nylén & Holmström, 2015). Although this technological discontinuity can destroy incumbent firms' core competencies (Anderson & Tushman, 1990) and drastically alter their strategic contexts (Bankewitz, Aberg, & Teuchert, 2016), it can also be an opportunity (Furr & Shipilov, 2019) if strategic leaders are able to adapt their mental models (Tripsas & Gavetti, 2000) and acquire the necessary resources and competencies (Loucks, Macaulay, Noronha, & Wade, 2016 (Erel, Stern, Chenhao, & Weisbach, 2018;Jarrahi, 2018). Furthermore, companies such as the Finnish software company Tieto have begun to appoint AI "members" to their leadership teams (Tieto, 2016). Although such decisions are met with skepticism and amusement by commentators, they highlight the need to align data-driven decision-making processes with classic models of corporate governance focused on people and accountability (Fenwick & Vermeulen, 2019). Further advances in machine learning (Jarrahi, 2018) also call for research on the possibilities for and consequences of deeper integration of AI as both a governing element and an element to be governed (Raisch & Krakowski, 2020).
Third, sustainability-related business practices are increasingly important for firms (Klewitz & Hansen, 2014). Technological innovation is likely to play a key role in enabling such practices (Fagerberg, 2018), and strategic leadership naturally influences their adoption (Rego, Cunha, & Polónia, 2017). However, we know little about whether and how anchoring sustainability in the TMT or the board affects firms' innovation processes. In particular, sustainable innovation practices require a shift of attention from economic performance towards environmental and social aspects (Wiengarten, Lo, & Lam, 2017). To achieve this shift, boards may need to reconsider CEO and TMT incentives. In this regard, future research can provide guidance on which incentives and performance indicators are most suitable for encouraging sustainable innovation processes and the development of sustainable products and services.
Finally, we see research opportunities in the fields of user innovation and open innovation, both of which differ from traditional, producer-focused innovation (Baldwin & Hippel, 2011). In user innovation, those using products, services, or processes are the source of innovations (Baldwin & Hippel, 2011). Open innovation is a "distributed innovation process that relies on purposively managed knowledge flows across organizational boundaries" (Chesbrough, 2017, p. 35), which includes opening firms' innovation processes to external knowledge sources (Chesbrough, Vanhaverbeke, & West, 2006). Both types of innovation require revisiting established knowledgemanagement and product-and service-development practices (Baldwin & Hippel, 2011). As such, they force strategic leaders to substantially adapt their mental models and behaviors. This creates a need to study, for example, the relationship between strategic leaders'

| PRACTICAL IMPLICATIONS
Our findings also have important implications for practitioners. First, our overview of the relationships between CEO characteristics and innovation outcomes provides board members with guidance for selecting a CEO who can successfully manage innovation given the firm's circumstances. For example, directors should carefully evaluate the potential CEO's educational background (e.g., Barker & Mueller, 2002), prior work experience (e.g., Deeds, DeCarolis, & Coombs, 2000), and other directorships (Oh & Barker, 2018), as these factors can affect the candidate's innovation decisions. In addition, boards need to consider environmental aspects, such as environmental dynamism (Nadkarni & Chen, 2014;Wu, Levitas, & Priem, 2005), as well as organizational aspects, such as the firm's experience with strategic alliances (Tyler & Steensma, 1998), as these factors moderate the relationship between CEO characteristics and innovation outcomes.
Second, the research summarized here provides boards with guidance regarding the use of managerial compensation to motivate the TMT to focus on long-term firm outcomes. Some examples include using stock options to mitigate CEOs' career-horizon issues (Zona, 2016) and focusing on long-term TMT compensation elements to foster innovation (Gopalan, Milbourn, Song, & Thakor, 2014).
Third, as our research comprehensively describes the individualand group-level effects of board characteristics on technological innovation, it can help shareholders with the challenging task of choosing appropriate directors given the organization's circumstances and the board's current composition. For example, if investors wish to increase the firm's patenting activity, they could consider selecting outside board members with experience in the focal innovation field.
Moreover, they may wish to increase the number of directors from ethnic minorities to enhance the firm's innovation output (Cook & Glass, 2015).

| LIMITATIONS
Our literature review has several limitations. First, we necessarily focused on a limited set of the most relevant journals. Naturally, there might be additional research on strategic leadership and innovation in other outlets. Second, the results of our review are based on a sample determined by a specific set of keywords. Although we followed an established and systematic process (David & Han, 2004;Rousseau, Manning, & Denyer, 2008) and although the large number of identified studies suggests that we cover a substantial section of the focal topic, the results are limited by the scope of the chosen keywords.
Third, we deliberately excluded studies focusing on young firms. Thus, researchers might wish to review the literature dealing with strategic leadership in the context of young firms to examine how this specific context affects the relationship between strategic leaders and innovation. Finally, we focused on technological innovation. Future research could review other forms of innovation, such as administrative, ancillary, or business-model innovation (Damanpour, 1987;Osiyevskyy & Dewald, 2015).

| CONCLUSION
In this interdisciplinary review, we aimed to unveil the relationship between strategic leadership and technological innovation. We not only summarized important aspects of this relationship but also stressed the need to extend this line of research. Beyond suggesting that researchers consider a wider range of theoretical approaches, our discussion of potential avenues for future research highlighted the fact that the role of the board of directors in innovation outcomes needs more attention. Moreover, our review reveals a need to better understand the impact of innovation on strategic leadership. Scholars should also exploit novel research settings in order to illuminate additional facets of the relationship between strategic leaders and innovation, and they need to ensure consistency and care in the measurement of innovation. To date, scholarship has led to the accumulation of a broad body of valuable knowledge on the relationship between strategic leadership and innovation. We are optimistic that our review will enable researchers to make even better use of this knowledge and further advance this promising field of research.