Gillespie started his coaching career at the College of the Canyons, a Californiajunior college. He started the school's baseball program in spring 1971 after the school's fall 1969 founding. In sixteen seasons as head coach, he had a 420-167 record.
Gillespie also played baseball at USC under coach Rod Dedeaux, and was a member of the 1961 College World Series champions. Along with Jerry Kindall, he is one of only two individuals who have both played for and coached a College World Series champion. He was succeeded as USC's head coach by Chad Kreuter, a former major league catcher who is also married to Gillespie's daughter Kelly.
National champion Conference regular season champion Conference regular season and conference tournament champion Division regular season champion Division regular season and conference tournament champion Conference tournament champion