A humorist could call this book "the enlargement of practically everything": NATO, the EU, the West European Union (WEU), the Organization for Security and Cooperation in Europe (OSCE), and the Council of Europe. Its authors are serious, however, in showing how and why these cases ranged from no enlargement (WEU) to cautious enlargement (NATO and the EU) to sweeping expansion (OSCE, Council of Europe). The chapter on NATO expansion disappoints by not probing the bizarre process of decision-making behind it, as American policymakers abruptly moved from supporting the Partnership for Peace to NATO expansion. Nor does it convey the intensity of the debate. But the chapter on the EU is more satisfactory. It points out that the European "federalist" vision has faded and predicts instead "differential integration" (varying degrees of integration for different members) as most likely for the future. The conclusion stresses the vagueness of the criteria for admission to these diverse organizations and underscores the different ways in which these conditions have been interpreted. The special importance of American and Russian roles is also given due recognition.