We live today in the world's first universal, multicultural, and multiregional system of sovereign states. Five centuries ago, emergent sovereign states were confined to Europe and contained within the bounds of Latin Christendom. Through five great waves of expansion this nascent European system globalized. The Westphalian settlement, the independence of Latin America, the Versailles settlement, post-1945 decolonization, and the collapse of the Soviet Union each brought a host of new states into the system. How can we explain these great waves of expansion, each of which saw imperial systems of rule displaced by the now universal form of the sovereign state? After detailing the limits of existing explanations, this article presents a new account of the principal waves of systemic expansion that stresses the importance of subject peoples' struggles for the recognition of individual rights. Empires are hierarchies, the legitimacy of which has been sustained historically by traditional regimes of unequal entitlements—institutional frameworks that allocate individuals of different social status different social powers and entitlements. In the Westphalian, Latin American, and post-1945 waves of expansion, which together produced most of today's sovereign states and gave the system its principal regions, subject peoples embraced local interpretations of new, distinctly modern ideas about individual rights and challenged the traditional distribution of entitlements that undergirded imperial hierarchy. Each wave differed, not the least because different rights were at work: liberty of religious conscience, the right to equal political representation, and after 1945, a compendium of civil and political rights. But in each case a “tipping point” was reached when the imperial system in question proved incapable of accommodating the new rights claims and subject peoples turned from “voice” to “exit,” and each time the sovereign state was seen as the institutional alternative to empire.