The Archives Association of Ontario (AAO) consists of approximately 300 members and represents archival institutions, those working in archives, as well as users and supporters of archives. Established in 1993 as a result of the amalgamation of the Ontario Association of Archivists and the Ontario Council of Archives, the Archives Association of Ontario is a network of archives and archivists providing programs, education, advocacy and shared knowledge.
To support its mandate, the AAO has both individual and institutional membership. The AAO offers a number of different services to its members, including guidelines for starting and managing an archives, continued training in management and preservation of archives, quarterly newsletters, advisory services, and access to the AAO Archeion archives database, to upload descriptions and digitized archival materials.