Leadership has been suggested to be an important factor affecting innovation. A number of studies have shown that transformational leadership positively influences organizational innovation. However, there is a lack of studies examining the contextual conditions under which this effect occurs or is augmented. Therefore, this study aimed to investigate the impact of transformational leadership on organizational innovation and to determine whether internal and external support for innovation as contextual conditions influence this effect. Organizational innovation was conceptualized as the tendency of the organization to develop new or improved products or services and its success in bringing those products or services to the market. Transformational leadership was hypothesized to have a positive influence on organizational innovation. Furthermore, this effect was proposed to be moderated by internal support for innovation, which refers to an innovation supporting climate and adequate resources allocated to innovation. Support received from external organizations for the purposes of knowledge and resource acquisition was also proposed to moderate the relationship between transformational leadership and organizational innovation. To test these hypotheses, data were collected from 163 research and development (R&D) employees and managers of 43 micro- and small-sized Turkish entrepreneurial software development companies. Two separate questionnaires were used to collect the data. Employees' questionnaires included measures of transformational leadership and internal support for innovation, whereas managers' questionnaires included questions about product innovations of their companies and the degree of support they received from external institutions. Organizational innovation was measured with a market-oriented criterion developed specifically for developing countries and newly developing industries. Hierarchical regression analysis was used to test the hypothesized effects. The results of the analysis provided support for the positive influence of transformational leadership on organizational innovation. This finding is significant because this positive effect was identified in micro- and small-sized companies, whereas previous research focused mainly on large companies. In addition, external support for innovation was found to significantly moderate this effect. Specifically, the relationship between transformational leadership and organizational innovation was stronger when external support was at high levels than when there was no external support. This study is the first to investigate and empirically show the importance of this contextual condition for organizational innovation. The moderating effect of internal support for innovation, however, was not significant. This study shows that transformational leadership is an important determinant of organizational innovation and encourages managers to engage in transformational leadership behaviors to promote organizational innovation. In line with this, transformational leadership, which is heavily suggested to be a subject of management training and development in developed countries, should also be incorporated into such programs in developing countries. Moreover, this study highlights the importance of external support in the organizational innovation process. The results suggest that technical and financial support received from outside the organization can be a more important contextual influence in boosting up innovation than an innovation-supporting internal climate. Therefore, managers, particularly of micro- and small-sized companies, should play external roles such as boundary spanning and should build relationships with external institutions that provide technical and financial support. The findings of this study are especially important for managers of companies that plan to or currently operate in countries with developing economies.