Transforming N.A.T.O.: New Allies, Missions, and Capabilities, by Ivan Dinev Ivanov, examines the three dimensions of N.A.T.O.s transformation since the end of the Cold War: the addition of a dozen new allies; the undertaking of new missions such as peacekeeping, crisis response, and stabilization; and the development of new capabilities to implement these missions. The book explains these processes through two mutually reinforcing frameworks: club goods theory and the concept of complementarities. N.A.T.O. can be viewed as a diverse, heterogeneous club of nations providing collective defense to its members, who, in turn, combine their military resources in a way that enables them to optimize the Alliance"s capabilities needed for overseas operations. Transforming N.A.T.O. makes a number of theoretical contributions. First, it offers new insights into understanding how heterogeneous clubs operate. Second, it introduces a novel concept, that of complementarities. Finally, it re-evaluates the relevance of club goods theory as a framework for studying contemporary international security. These conceptual foundations apply to areas well beyond N.A.T.O. . They provide useful insights into understanding the operation of transatlantic relations, alliance politics, and a broader set of international coalitions and partnerships.