This essay interprets John Locke's teachings about private societies, or free private associations. The essay proceeds by interpreting Locke's mature writings on ethics, politics, and philosophy, and then by illustrating Locke's teachings as they apply to two contemporary problems in associational freedom. Although Locke wrote about private societies primarily in the course of arguing for religious toleration, throughout his mature corpus he develops an internally consistent general theory of associational freedom. At first glance, Locke seems to suggest that all citizens (...) are entitled to associate for any end of their choosing, to control admission into and expulsion from their membership, and to enforce their own internal rules of governance. However, Locke qualifies this broad right to bar societies from organizing around ends inconsistent with the minimal moral and political conditions of liberalism. Ultimately, Locke suggests, citizens deserve a broad right of private society only to the extent that they are well enough formed by their regime and its private institutions to be capable of governing themselves in both private and public life.In contrast with contemporary practice, Locke's justification is broader in some respects and narrower in others. The essay illustrates the implications by considering how Locke's teachings justify limiting the scope of anti-discrimination laws and enlarging the scope of government efforts to dissolve seditious associations. (shrink)