Holmes' first musical foray was with his wife Katherine in the folk pop parody duo, Allen & Grier. Following military service, he resumed his music career. Among the highlights: Holmes put lyrics to Bob Gaudio's music on The Four Seasons' 1969 "Genuine Imitation Life Gazette" album, after which the pair went on to compose Frank Sinatra's 1970 "Watertown" album. Coming during a relative low point in Sinatra's career, "Watertown" was his least successful album, but the song "I Would Be in Love (Anyway)" reached No. 4 on the "Billboard" Adult Contemporary chart. The song "What's Now is Now" reached No. 31 on that chart and was later included in "Frank Sinatra's Greatest Hits Volume 2". Sinatra's recording of the Gaudio-Holmes composition "Lady Day" was left off the "Watertown" album, but was released as a single, and Don Costa later rearranged "Lady Day" for inclusion in Sinatra's "Sinatra & Company" album. In 1985, Nina Simone recorded a cover version of "For a While", from the "Watertown" album, for her "Nina's Back" album. That same year, she recorded a live version of "For a While" for her "Live And Kickin album.