International Relations and Scientific Progress contends that a theory focusing on the structure of the international system explains a wider and more interesting range of events in world politics than other theories. Such theorizing appears to be out of favor as the result of the apparent failure by structural realism, the most prominent system-level theory over the last two decades, on any number of fronts--most notably an inability to anticipate the ending of the Cold War and its aftermath. This new book is put forward as the most comprehensive and innovative theoretical work on paradigms in international relations since the publication of Theory of International Politics, which created structural realism, more than two decades ago. With appropriate revisions, however, structural realist theory can compete effectively and reclaim its primacy. The first part of International Relations and Scientific Progress 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 reviews structural realism within that context and identifies a lack of connection between theory and research that links power-based indicators to international conflict, crisis, and war. This part of the book makes the case for an elaboration of structural realism by showing that a system-level theory based on structure has great unrealized explanatory potential. By comparison, the current overwhelmingly research oriented agenda on state dyads imposes severe limitations on understanding that are not currently appreciated. Part Three sums up the work and explores new directions, most notablyas related to empirical testing of an elaborated version of structural realism that focuses on both continuity and change in the international system.