Two central features of global history over the past century have been the pre-eminent power of the United States in world politics and the growth of international organizations. The relationship between these phenomena has been variously interpreted, in ways that reflect theoretical and methodological commitments as well as political perspectives. The Realist school, for whom power relationships are always determinative, have followed Carl Schmitt and E. H. Carr in seeing international institutions, and the norms and laws they uphold, as instruments through which dominant powers seek legitimacy as well as influence. By contrast, liberal theorists have viewed the pursuit of a rule-governed world order, and the development of the idea of a ‘world community’, as a more autonomous and broadly based enterprise, one spurred by increased interdependence and greater concern with matters of common interest to all nations – not least that of avoiding the devastating effects of great power warfare in the modern era. As is usually the case with such analytically sharp distinctions, neither of these positions conveys the whole truth. From the Concert of Europe on, great powers have recognized a collective interest in peace and stability but the growth of international institutions has also been the product of wider ideals and interests. As Mark Mazower has shown in his wide-ranging study, Governing the world, the relationship between the narrower interests of great powers on the one hand and various forms of internationalism on the other has been a complex one, involving elements both of conflict and of congruence. But, Mazower emphasizes, since the Second World War, the structure and activities of the United Nations, the International Monetary Fund, the World Bank, and other international organizations have been largely shaped by Washington. A generation earlier, however, the United States did not even become a member of the League of Nations, making it more possible to distinguish between the role of American power and that of other sources of support for international bodies, and also to assess the relationship and comparative importance of these two novel elements in world politics. It is perhaps not surprising that much of the recent scholarship on the international history of the post-First World War period has focused, in one way or another, on this issue.