For the first two seasons, music (including the theme) was composed by David Shire in a strongly country-music fashion. During the third season, there was no regular composer, with four different closing themes used in five episodes. The main title theme used in most openings and all closings from "Butch Cassidy Rides Again" (episode 4.1) was never given screen credit, but its resemblance to other scores in the fourth season suggests that Frank De Vol (My Three Sons, The Brady Bunch, Fernwood 2Night) composed all or most of the theme. The theme is somewhat similar in a driving beat to others which series producer Glen A. Larson composed for later series such as Switch and Sword of Justice.