Only a social scientist could ever have believed that material interests alone drove history and that ideas were only epiphenomenal. In this volume, a group of distinguished social scientists documents the ways in which ideas have taken on lives of their own and played key roles in structuring international relations. Chapters on the postwar economic order, Stalinism, human rights, decolonization and the European Community chronicle the complex way in which ideas and material interests interact. Among the most interesting is Stephen Krasner's article debunking the notion that the 1648 Peace of Westphalia marked a decisive break with medieval concepts of sovereignty. One glaring omission: the role of ideas in the collapse of communism.