In spite of its widespread use, no one has ever stated clearly what the distinction between bipolar and multipolar systems refers to. Moreover, some common definitions of “bipolarity” imply behavior that is inconsistent with the behavior of states during the cold war. This article argues that the distinctive feature of post–World War II international politics was not that two states were more powerful than the others, as the literature on bipolarity would suggest, but that one state, the Soviet Union, occupied in peacetime a position of near-dominance on the Eurasian continent, a position that states in the past had been able to achieve only after a series of military victories. This fact explains the behavior that others have sought to explain by bipolarity, as well as behavior that is inconsistent with what common definitions of bipolarity would lead us to expect. The article concludes with a discussion of the implications of the argument for structural theories of international politics and controversies about what lies ahead.