The Great Lakes Chapter of the American Theatre Organ Society (GLC-ATOS) is a nonprofit organization dedicated to the preservation of the Theatre Pipe Organ and its music. GLC-ATOS is a chapter of the American Theatre Organ Society. The objectives of the Great Lakes Chapter and the American Theatre Organ Society are to preserve, maintain, restore and promote the surviving theatre pipe organs from the '20s and '30s. This effort also promotes the use, understanding and enjoyment of these unique instruments by today's generation as well as future generations.