In the latter half of the twentieth century, war among states has become increasingly rare. More significantly, states in some regions of the world, i.e. in Europe, Southeast Asia, and South America, have come to neither expect nor prepare for war against each other. Such zones of peace (or security communities), through their proliferation and expansion, hold the promise for a fundamental transformation of world politics. After briefly introducing students to the range of International Relations theories on interstate war and peace, this course will focus on constructivist approaches that explain the formation of such zones of peace through the development of shared norms, values, and a sense of collective identity among states. Then, these constructivist arguments will be applied to analyze the possible transformation of Turkish/Greek relations through the expansion of the European zone of peace.