'This book should be of interest to all students of international politics, and, of course, especially to those interested in theory.' - Kenneth N.Waltz, Ford Professor of Political Science, University of California This book reviews classical and contemporary theories of international relations, and it does so on the basis of four interrelated worldviews. Worldviews are simple but basic devices; they are characterized, on the one hand, by the duality of war and peace, and, on the other hand, by the duality of anarchy and hierarchy. Worldviews permit the isolation of concepts central to describing and analyzing international relations and are superior to such well-known categories as the billiard-ball, the cobweb, and the layer-cake approach.