This chapter explores how liberal internationalism, the order’s animating 'regime of thought and action', has addressed the question of cultural diversity. It argues that liberal internationalism evinces no simple or singular theory about cultural diversity, and that since the nineteenth century four different approaches are apparent, combining, at distinct moments in time, to form what we see here as distinctive liberal diversity regimes. These approaches are to build a liberal order on the pluralism of Westphalian sovereignty; to confine issues of culture within domestic civil societies; to foster ideas of modernization that would in time erase global cultural differences; and to construct institutions of 'exclusion,' manifest in political hierarchies and, at the extreme, formal empire. In the late nineteenth and early twentieth centuries, civilizational and racial prejudices informed how these approaches were interwoven, but by the end of the Cold War these had been replaced with more universalistic conceptions of human rights, multiculturalism, and civic nationalism. It was at this very moment, however, that the now-globalized liberal international order revealed its limits.