Membership in the Association of Oregon Counties is open to all Oregon county governments. Currently, all 36 counties are members. Dues are assessed on an annual basis. Elected county commissioners and county judges represent their respective counties as voting members.
AOC affiliate members are statewide associations where the voting membership is primarily composed of elected county officials other than commissioners and judges, or where the voting membership is primarily composed by professionals who have significant administrative responsibility and authority in an Oregon county.
Associate organizations of AOC are statewide associations whose voting membership consists primarily of Oregon county department directors who serve at the pleasure of a board of county commissioners, a county court or a county administrative officer.
AOC has a Business Partner Program designed to facilitate interaction between business and government and improve understanding of the challenges each faces. The Business Partner Program offers business leaders a forum to make their concerns known to county officials in a beneficial way. The Program is set up to foster personal relationships between the public and private sectors.