Originally founded in 1861 as the Teachers' Association of Canada West (TACW), the Ontario Educational Association (OEA) was a fixture on the education scene in Ontario for one hundred twenty-five years until its dissolution on November 28, 1985. This article traces the early development and maturation of the OEA to focus on its involvement in curriculum reform undertaken by Liberal and Progressive Conservative governments in the early twentieth century. As a non-state entity, the OEA nevertheless had close ties to and received financial support from the state. It regularly advised the Department of Education on matters related to education and contributed to the building of the educational state. The annual conventions of the OEA attracted transnational participation and provided a space for educationists to exchange knowledge as well as form networks and alliances to advance their interests in education. This article locates the formation of OEA as part of the phenomenon of association that Alexis de Tocqueville identified in nineteenth century America. While mid-nineteenth century Ontario was not America, it was nevertheless a liberal capitalist society and the concept of desiring to act in political self-interest for what was deemed good for education and society underlay the creation of the Association. De Tocqueville's focus on the importance of political associations was linked to understanding the capacity of liberal democracies to govern in the nineteenth century. This approach makes possible to understand the OEA as a site where processes of building and governing the educational state were enacted through association.