Failure to address unsustainable global change is often attributed to failures in conventional environmental governance. Polycentric environmental governance—the popular alternative—involves many centres of authority interacting coherently for a common governance goal. Yet, longitudinal analysis reveals many polycentric systems are struggling to cope with the growing impacts, pace, and scope of social and environmental change. Analytic shortcomings are also beginning to appear, particularly in the treatment of power. Here we draw together diverse social science perspectives and research into a variety of cases to show how different types of power shape rule setting, issue construction, and policy implementation in polycentric governance. We delineate an important and emerging research agenda for polycentric environmental governance, integrating diverse types of power into analytical and practical models. © 2019 The Authors