Local government managers are described as key participants in the development of interlocal cooperation, but the interests of city councils in this process have gone largely unstudied. Here, the author addresses the theoretical importance of council-manager relations in interlocal public service cooperation. Three propositions identify areas of shared council-manager responsibility. Evidence from in-depth interviews with city council members is used to assess each proposition. While interlocal partnership has been described as a managerial activity, council members take an interest in network development and agreement assessment. Managers, on the other hand, give greater attention to public participation and education. The evidence refines assumptions about council-manager roles in the formation of cooperative agreements, with important implications for local government management.