One useful way to understand these changes is to trace the evolution of the Model City Charter. Studies of the diffusion of innovation show that professional and interest associations are often the carriers of change. The National Civic League (NCL), founded in 1894, is the oldest continuing association of those interested in cities and how they are govemed. In its first sixty years, the NCL would have been categorized as a "good govemment" association, good govemment being understood to mean clean and wellmanaged govemment. One of the many ways the NCL went about achieving its purposes was to devise a Model City Charter and to press for the adoption, in as many cities as possible, of some or all of its features. First published in 1900 and revised six times since then, the charter provides a detailed history of the shifts from political to administrative cities. In recent years, the Model City Charter has struggled with the meaning of adapted cities. Because of its importance in the diffusion of innovation and its usefulness as a historical description of structural dynarnics, we describe in detail the evolution of the National Civic League's Model City Charter.