The end of the cold war has provoked an explosive increase in theories, concepts, and debates in the discipline of international relations. There is growing confusion as to what are the important issues and what are the best ways of approaching them. This book aims to provide a systematic introduction to principal theories in IR, including "post-positivist" theories which have gained prominence in recent years. The strengths and weaknesses of each theory are critically examined and the main points of contention between the theories are discussed. The text contains empirical illustrations which demonstrate the link between theory and actual events. It provides a rapid entry into the discipline of IR. Each chapter begins with a brief summary, and ends with a list of key points, study questions, and a guide to further reading.