Bruce Bueno de Mesquita, who set the standard for the scientific approach to international relations, has returned with a reformulated fifth edition of Principles of International Politics, based on extensive reviewer feedback and newly guided by an emphasis on questions about the causes and consequences of war, peace, and world order. More than ever, the strategic perspective in international relations is examined with complete clarity, precision, and accessibility. What hasn't changed is Principles' coverage of the fundamentals of IR. The foundational topics are given sustained treatment: the major theories of war, the domestic sources of international politics, the democratic peace, the problems of terrorism, the role of foreign aid, democratization, international political economy, globalization, international organizations and law, human rights, and the global environment. No other introductory text delivers such an easily-understood contemporary explanation of international politics, while truly enabling students to learn to mobilize the key concepts and models.