Since the end of the Cold War, activists and scholars alike have celebrated the phenomenal growth of transnational social movements across the globe. For some, this new eruption of grass-roots political activism on a world scale – from the Rio Earth Summit to the Seattle anti-globalization protests – represents the emergence of a global or transnational civil society. This book provides a critical survey of recent approaches to the study of civil society and international relations, presenting an alternative historical and sociological account of the interaction between these two spheres. It makes a theoretical case for the importance of social movements in world politics arguing that modern social movements emerging out of civil society have been instrumental in shaping the contemporary international system. In this wide-ranging engagement with past and present controversies in international relations, Colás shows how a renewed conception of international civil society can illuminate future possibilities for international social movement activity. This book will be of great interest to students and scholars of international relations, political sociology and social history, as well as those who seek to play a part in global politics.