International Relations and Scientific Progress argues that a theory focusing on the structure of the international system may explain a wider and more interesting range of events in world politics than other alternatives. The first part of the book assesses the meaning of progress in the discipline of international relations, a process that culminates in the creation of a new concept, the scientific research enterprise. The second part review structural realism within that context and makes the case for an elaboration of structural realism by showing that a system-level theory based on structure could have great unrealized explanatory potential. The third part explores new directions, most tably as related to empirical testing of an elaborated version of structural realism that focuses on both continuity and change in the international system. Patrick James is professor of political science at the University of Missouri.