Next door to the Cassidy Room, the attached Bar 20 Theatre will seat up to 150 theater style. Full classroom/meeting capabilities include a stage with podium, projection screen and projector, as well as sound and video equipment. The Bar 20 Theatre is equipped for wireless internet access.

The Bar 20 Theatre is also the location of the Silver Screen Cowboy Museum, a large collection of memorabilia from the Silver Screen Cowboys, from the early, little-known cowboys, to the major Cowboys, such as Tom Mix, Gene Autry, Roy Rogers and Hopalong Cassidy.