Scholars of social policy development in the United States and elsewhere have recently focused on the historical and contemporary importance of complex, delegated welfare state governance. In this article, I outline the emergence of a coordinated urban welfare state in the city of Toronto between 1870 and 1929, describing the creation of both public and private forms of coordination and centralization. I argue that we must understand social policy development in this period as resulting from the interaction of three policy coalitions: municipal traditionalists, municipal progressives, and social work professionals, and that social policy centralization occurred as a result of an alliance between municipal progressives and social work professionals. To explain the long-term development of social policy in Canada and elsewhere, I argue, we must understand the interaction among these internal coalitions in the social policy field and the ways that broader fiscal and cultural changes strengthened or weakened each coalition over time.