This article analyzes Rousseau’s political theory of private property, fills a lacuna in the literature, and develops a novel interpretation of Rousseau’s apparently contradictory remarks. Although Rousseau was critical of private property, he did not advocate a clear and easy solution to the problems he discerned. Instead, he put forth a highly differentiated perspective that was principled and pragmatic. He rooted the legitimacy of private ownership in an ideal theory of republican property rights, which refers primarily to the normative principle of reciprocity. In his opinion, a balance of private property rights is indispensable to a well-ordered society and a just republic not only because it binds the state, society, and citizen together, and not only because it secures the independence of individual citizens from each other, but also because it enhances political legitimacy and reciprocity. On these principled grounds, Rousseau’s theory rules out “collectivist” solutions as much as vast differences in wealth and “absolutist” theories of more or less unlimited private property rights. Instead, his theory builds on the republican idea of private property as a public political institution. Within this ideal framework, Rousseau allows for certain non-ideal deviations in particular circumstances on prudential grounds.