Openness in the international economy happens when countries employ the commercial policies needed to mould free trade into an outcome that serves their national interests. With this conclusion, John Kroll challenges previous attempts to explain movements between free trade and economic closure solely in terms of domestic politics, international distributions of power, or market crises. He demonstrates that the final outcome of economic cooperation or conflict is more complex, determined both by the anarchical structure of international politics and by the policies nations employ to cope with that anarchy. Establishing a theoretical framework that links commercial policies to systemic outcomes, Kroll is able to offer a unique solution to the current debates over trade policy. He takes the major elements of that debate such as calls for aggressive reciprocity, enhanced multilateralism, and expanded trading blocs and establishes how and why each of these policies can influence the stability or instability of free trade systems. Kroll reviews how the GATT has enhanced free trade in the past by institutionalizing some of those policies and explains how GATTs failure to implement other policies will leave it ill equipped to handle future challenges. Kroll combines trade theory and recent works on anarchical cooperation, thereby responding to two recent admonitions in the international relations literature: He eschews ad hoc hypotheses in favor of ones derived from deductive models, and he moves game theory analysis beyond modelling and into the derivation of falsifiable propositions. In the latter book chapters, the author tests his proposition against a case study of British and German behavior during the collapse of free trade in the late nineteenth century.