Knowledge-intensive services are seen to have an increased importance for learning and innovation activity in a more knowledge-based economy. This paper compares the relevance of two complementary approaches as analytical tools in studying the exchange of knowledge-intensive services in innovation processes. The first approach focuses on the importance of expert knowledge from companies in the KIBS (knowledge-intensive business services) sector as input in innovation processes. The other approach focuses on the role of knowledge-intensive service activities (KISA) in innovation processes. The latter approach regards a wider set of players as potentially important knowledge-intensive service providers than just KIBS firms, it focuses on knowledge exchange beyond market relations, and it emphasizes the mix and match of internal and external knowledge-intensive services. This paper analyses the relevance of the two approaches by studying the use of knowledge-intensive services in two Norwegian industries dominated by different knowledge bases, that is, the aquaculture and the software industry, respectively. Empirical studies in the two industries demonstrate that the KISA approach certainly brings new elements into the investigation of the role of knowledge-intensive services in innovation activity. The approach focuses on how knowledge exchange occurs (in static or dynamic ways), and how it relates to firms' own innovation processes. However, innovation studies can also benefit from differentiating more between different types of firms, for example, firms in different phases of their life cycle.