A decade after the end of the Cold War, the debate about structural realism in general and Theory of International Politics in particular had heated up. Twenty years earlier, Kenneth Waltz had developed an explanation of international affairs based on three components: (1) the international system’s ordering principle (e.g., anarchy vs. hierarchy); (2) the differentiation of units and their functions; and (3) the number of dominant units. The demise of the Soviet Union potentially reflected a significant change in the third component of Waltz’s theory: some observers claimed that a unipolar moment had emerged, while others pointed to the rise of multipolarity, changes in the number of dominant units that could be expected to produce observable differences in international behavior and outcomes. Democratic peace theorists, globalization boosters, and prophets of the Information Revolution also pointed to potential changes in the system’s ordering principle (component one). Waltz suggested that a unipolar moment would be fleeting (and that the world remained more bipolar than many believed), and that a democratic peace and associated transformational ideologies would not change the system’s ordering principle, leaving critics to revisit the “static” nature of Waltz’s theory and thinking.