Brian Rathbun’s Trust in International Cooperation is one of the more important books in recent years written about American foreign policy and multilateral cooperation in world politics. While historians of American foreign policy will find much of interest in the empirical chapters on the origins of the League of Nations and NATO, Rathbun’s primary task is to challenge how International Relations [IR] theorists think about the origins of cooperation. In his view, “the way that most in the field go about explaining international cooperation and the creation of international organizations, as the rational and functional response to objective security environments marked by uncertainty, is almost always too narrow, often obvious, and sometimes exactly wrong” (xi). In contrast to rationalist approaches, which view the creation of multilateral institutions as necessary for the establishment of subsequent relations of trust among states, Rathbun argues that the causal relationship is exactly the opposite: “Trust rather than distrust leads states to create international institutions. It is a cause, not the effect, of international organizations” (5).