Among Vincent Ostrom's many contributions to the study of public administration, policy, and political science, the concept of polycentricity remains his single most important legacy. This essay locates the origins of this concept in Ostrom's early research on resource management in the Western United States and demonstrates its continuing influence throughout The Intellectual Crisis in Public Administration, The Political Theory of a Compound Republic, and his other major publications. Although typically pigeonholed within the confines of the public choice tradition, Ostrom's body of work should be widely appreciated as an early statement of the critical importance of network forms of governance in democratic societies.