Now in a thoroughly revised and updated edition, this classic text presents a comprehensive survey of the many alternative theories that attempt to explain the causes of interstate war. For each theory, Greg Cashman examines the arguments and counterarguments, considers the empirical evidence and counterevidence generated by social-science research, looks at historical applications of the theory, and discusses the theory’s implications for restraining international violence. Cashman examines theories of war at the individual, substate, nation-state, dyadic, and international system levels of analysis. Written in a clear and accessible style, this interdisciplinary text will be essential reading for all students of international relations.