 Michele Tobin played his sister, Mo, on the show, and they later worked together on "California Fever".McNichol sang the show's theme song and in 1978 recorded an album with his sister, "Kristy and Jimmy McNichol", produced by Phil & Mitch Margo.The album spawned one hit single, a cover of The Chiffons' "He's So Fine", which charted at #70 on the Billboard Hot 100 in August 1978.