The past decade has witnessed a growing interest among scholars of international relations, and global environmental governance in particular, in the role of transnational networks within the international arena. While the existence and potential significance of such networks has been documented, many questions concerning the nature of governance conducted by such networks and their impact remain. We contribute to these debates by examining how such networks are created and maintained and the extent to which they can foster policy learning and change. We focus on the Cities for Climate Protection (CCP) program, a network of some 550 local governments concerned with promoting local initiatives for the mitigation of climate change. It is frequently asserted that the importance of such networks lies in their ability to exchange knowledge and information, and to forge norms about the nature and terms of particular issues. However, we find that those local governments most effectively engaged with the network are mobilized more by the financial and political resources it offers, and the legitimacy conferred to particular norms about climate protection, than by access to information. Moreover, processes of policy learning within the CCP program take place in discursive struggles as different actors seek legitimacy for their interpretations of what local climate protection policies should mean. In conclusion, we reflect upon the implications of these findings for understanding the role of transnational networks in global environmental governance.