This dissertation explores republican thought in the early modern period in order to rethink how we regard authority in contemporary political life. The study challenges the neo-republican derivation of legitimacy from individual freedom in order to retrieve the emphasis on constitutional design and mores that energized early modern republicanism. I turn to early modern writers such as James Harrington (1611–1677), the third Earl of Shaftesbury (1671–1713), Montesquieu (1689–1755), and Jean-Jacques Rousseau (1712–1778) to consider how political institutions and persons ought to embody authority. The retrieval of authority as a central concern for early modern republicans changes our understanding of the republican problematic both then and now. When neo-republicans prioritize freedom as the linchpin of republican government, they introduce a tension between government that secures individuals against domination and government controlled by the people. A constitutive tension runs through early modern republican vocabularies, but it is not that between liberty and democracy. Rather, liberty and democracy constitute a coextensive preserve placed in productive tension with the principle of authority. The dilemma organizing republican theory in the early modern period is the classical one between democratic and aristocratic institutions and manners. The desideratum of the mixed constitution is republican legitimacy, not individual freedom. From the early moderns we learn that republican legitimacy requires the simultaneous affirmation of popular power and aristocratic judgment, of liberty and authority.