History and theory are all too often treated as separate approaches to international relations. This book offers an accessible synthesis of sophisticated theory and in-depth history. The uses of theory are examined in the opening section which includes a defence of the historical method by John Lewis Gaddis and the arguments for a more scientific method by Bruce Bueno de Mesquita. The subsequent chapters of the book take major issues and episodes in international relations since 1945 (such as the rise of Japan, change in Latin America, wars in the Middle East, and decolonization) and demonstrate how it is that particular theories assist in explaining them. These include theories of power, cooperation, alliances, empire, integration, and arms control. The student is left with a nuanced view of history and a critical but constructive approach to theories of international relations. The book challenges both students and academics to think afresh about the ways they analyse international relations.