References to the Peace of Westphalia have played an important role in the discourse of international relations. Originally referred to as a concrete historical event and associated with a variety of meanings, such as the triumph of state sovereignty, the establishment of a community of states, and even the beginnings of collective security, the Peace was later transformed into a conceptualization of the international system. Beginning in the late 1960s, phrases like “Westphalian system” came to convey a package of ideas about international politics limited to the supremacy of state sovereignty, territoriality, and nonintervention, to the exclusion of other meanings. This conceptualization serves as a popular and convenient contrast to a more globalized order, but there are problems with its use: first, because the Westphalian system is an ideal-type that might never have actually existed, the impact of globalization may be exaggerated by scholars who employ it. Second, its use implies a linear progression from some Westphalian configuration toward some “post-Westphalian” state of affairs, whereas actual system change is likely to be more complex.