This paper pursues the development of a theoretical framework that explains interactive learning between innovating firms and external actors in the knowledge infrastructure and the production chain. The research question is: what kinds of factors explain interactive learning of innovating firms with external actors? In our theoretical framework we augment the resource-based perspective predominant in network theory with an activity based account and a structural account of interactive learning. We contend basically: that higher technological dynamics induce innovative activities with a higher complexity. More complex innovative activities increase the probability of internal resource deficits/shortages in the innovating firms. The higher the resource deficits/shortages and the lower the alignment of innovative activities the more likely the search for complementary resources externally, which increases the likeliness of external relationships. In order to test the generality of our theoretical claims we analyse our models within four sectors with different technological dynamics as distinguished by Pavitt. Furthermore we estimate four models within each sector predicting: 1) the level of interactive learning of innovating firms with the public knowledge infrastructure (difficult to access, demands high internal competences to utilise scientific knowledge), 2) the level of interactive learning of innovating firms with the production chain (easy to access), 3) the level of interactive learning of innovating firms with their users (here the innovating firms are the producers), 4) the level of interactive learning of innovating firms with their suppliers (here the innovating firms are the users), 5) the level of interactive learning with competitors. These analyses allow for a comparison between interactive learning with different external actors and give deeper insights into the differentiated interaction patterns governing innovation. Our fmdings show that patterns of interactive learning between sectors differ. Some are more resource based and others are more affected by the complexity of innovative activities. Particularly the interactive learning with the knowledge infrastructure differs from that with actors in the production chain
