Co-opetition, simultaneous co-operation and competition, is a recent phenomenon. Co-opetition entails sharing knowledge that may be a key source of competitive advantage. Yet, the knowledge gained by cooperation may also be used for competition. There is little investigation of how this problem may be modeled and, hence, managed. A game-theoretic framework for analysing inter-organisational knowledge sharing under co-opetition and guidelines for the management of explicit knowledge, predicated on co-ordination and control theory has been proposed, but remains untested. This research empirically investigates these issues in the context of small and medium-sized enterprises (SMEs). SMEs provide an interesting setting as they are knowledge generators, but are poor at knowledge exploitation. The paper uses data from UK SMEs to investigate co-opetition, management of knowledge sharing and the role of IS.