His early theatre training began at the Pacific Conservatory of the Performing Arts at Allan Hancock College in Santa Maria, California,[1] where his talent and rich baritone voice were showcased in leading roles in plays, musicals, and opera.

[2] Gaines has appeared in a number of films and television shows, including Fame, Frasier, L.A. Law, Law & Order, and Piece of Cake, but his most notable television role was as Mark Royer, who married Valerie Bertinelli's Barbara Cooper on TV's One Day at a Time.

He also portrayed Coach Brackett in the 1981 movie Porky's, Lt. Ring in the 1986 film Heartbreak Ridge and Jason in The Sure Thing (1985).

[8] He has appeared Off-Broadway, starting in 1978 with Spring Awakening and recently The Grand Manner by A. R. Gurney at Lincoln Center in 2010.

[9][10] In regional theatre, Gaines appeared in Our Town at the George Street Playhouse, New Jersey, in April 2014.