This was written by Bruce Johnston, who is a member of The Beach Boys. The song is sometimes erroneously rumored to be about Brian Wilson. Johnston cleared this up when he told us: "The Captain & Tennille were the first artists to record my song 'I Write The Songs.' I never wrote 'I Write The Songs' about Brian Wilson. I wrote it about 'where music comes from' (for me, music comes only from God). My song has nothing to do with Brian! I admire Brian Wilson's great melodies and, as a member of the Beach Boys, I'm singing these fantastic songs in concert year after year."
Teen heartthrob David Cassidy released a successful version that was a single in England and hit #11 on the UK charts. Clive Davis, who was in charge of Manilow's record label, heard Cassidy's version and had Manilow record it.
This won a Grammy for Song of the Year. The Beach Boys never won a Grammy - after winning this, Johnston became the only member of the group to get one until Brian Wilson's "Mrs. O'Leary's Cow" was awarded Best Rock Instrumental Performance in 2005.
From the liner notes of The Complete Collection And Then Some...: Manilow was originally reluctant to record this song, saying to Arista Records chief Clive Davis, "This 'I Write The Songs' thing Clive, I really don't want to do it." Manilow says his worry "was that the listeners would think I was singing about how "I" write the songs, when it was really about the inspiration of music. Clive understood, but didn't think it would be a problem. "Besides," he told me, "You DO write songs!" Manilow says he was concerned about coming off as a gigantic egomaniac, but that he liked the song so much he decided to record it. He adds, "Whenever I heard the song in public, I felt the need to run to everyone who was listening and say, 'You know, I'm really not singing about myself!'"