American Theatre Organ Society (ATOS)
ATOS – London and South of England Chapter
ATOS Conventions – USA
Australia – Queensland (TOSA Q)
Australia – Stirling Theatre Organ Productions (STOP), Perth
Australia – Victoria (Melbourne Theatre Organ)
Australia – Warragul Theatre Organ Society (Victoria)
Cinema Organ Society – UK
Columbia River Theatre Organ Society – Oregon and Southern Washington
Delaware Valley Theatre Organ Society (TOSDV) – Phoenixville
Dickinson Theatre Organ Society – Wilmington, Delaware
Garden State Theatre Organ Society – New Jersey
Lancastrian Theatre Organ Trust – UK
Los Angeles Theatre Organ Society
Motor City Theatre Organ Society – Detroit
NOR-CAL Theatre Organ Society – Northern California
North East Theatre Organ Association – Howden le Wear, Crook, Co. Durham
North Texas Chapter, American Theatre Organ Society
Orange County Theatre Organ Society – Fullerton, California
Puget Sound Theatre Organ Society – Seattle, Washington
Rochester Theatre Organ Society – Rochester, New York
Sooner State Chapter, ATOS – Tulsa, Oklahoma
Theatre Organ Club – UK
Valley of the Sun Chapter, ATOS – Phoenix, Arizona
Virtual Theatre Pipe Organ Group for those interested in computer based virtual theatre organs
Western Reserve Theatre Organ Society (Cleveland, Ohio ATOS Chapter)