What is the relationship between social movements and polycentric governance? The concept of polycentricity has been at the center of recent debates in environmental governance. While most of this work has analyzed polycentric arrangements in relation to collaborative and adaptive governance, some have recently focused on how political conflicts shape these arrangements. In this paper we build on this work through Luther Gerlach's forgotten framework of polycentric social movements to undertake the task of politicizing polycentricity. This task entails expanding the analytical focus of institutional analyses of polycentricity and examining the social group politics of social movements. To this end, we present a case study of the climate justice movement and its relation to climate change governance. We analyze whether and to what extent the movement has embodied polycentric arrangements throughout its history, and to what effects. We show that show that, in seeking to address the multiscalar nature of environmental problems and the limits of existing institutional arrangements, climate justice groups are increasingly organized in a polycentric fashion. Climate justice groups mobilize multiple strands of environmental justice movements from the global North and South, as well as from indigenous and peasant rights movements, and it is organized as a decentralized network of semiautonomous, coordinated units. We find that this strategy generates new opportunities and challenges for the movement, and thus has important implications for its effectiveness in achieving these transformations. Lastly, we find that through these polycentric arrangements, movements such as that for climate justice are able to exert simultaneous influence on multiple sites of environmental governance, from the local to the global, furthering increased polycentricity in formal institutional arrangements.