[1] ATOS consists of regional member-chapters, and is led by democratically elected leaders.

There are currently over 75 local chapters of ATOS, and membership is made up of musicians, technicians, hobbyists, educators, and others who enjoy the music of the theatre organ.

[2] ATOS was founded as a group called the American Theatre Organ Enthusiasts by Richard Simonton.

He arranged a gathering at his home on February 8, 1955, where he and several other organ enthusiasts founded what would later become ATOS.

[3] ATOS has outreach to young musicians, and funds several musical scholarships for youth members.