Criss is given co-writer credit for the
ballad "Beth", which was a Top 10 #1 hit for Kiss in 1976. The song remains the number one hit song for Kiss in the USA and it earned them a People's Choice Award for "Young People's Favorite New Song" in 1977 which had tied with "Disco Duck".
The song was written before Peter had joined Kiss, while he was in a band named Chelsea. Peter came up with the melody for the song while on a train to New York City from New Jersey where the band practiced. He and a fellow band member of Chelsea, guitarist Stan Penridge, wrote the song together. " Later, the two would form a band named Lips.
A bootleg exists of the song from 1971, but the song's title was "Beck", named after fellow band member, Mike Brand's wife, Becky who would call often during their practices to ask Mike when he was coming home. Years later, while in Kiss, both Bob Ezrin and Gene Simmons are credited for changing the song's title to, "Beth". The song was said to be a tribute to Criss' wife Lydia, and according to interviews with Peter, he had changed some of the lyrics to reflect some of Lydia's lamenting that she missed him while on tour, but the song originated years earlier with the band Chelsea.
Among Beth, other songs he sang in Kiss were Black Diamond, Hard Luck Woman, Dirty Livin', Nothin' to Lose, Mainline, Strange Ways, Getaway, Baby Driver, Hooligan, and I Finally Found My Way, with only the first one being a live staple for every tour during his time with Kiss and Dirty Livin', Baby Driver, Hooligan and Beth being the only ones he co-wrote (Paul Stanley wrote Black Diamond, Hard Luck Woman, Mainline, and I Finally Found My Way) (Ace Frehley wrote Strange Ways and Getaway) (Gene Simmons wrote Nothin' to Lose).