Brooklyn's Neil Diamond composed "I'm a Believer" first although it wasn't released as a single. It can be found on the albums: "Just for You", "September Morn" and "Classics". Neil has sung the song as a slower number in concert.

Don Kirshner put the group together and Mickey Dolenz of The Monkees sings the lead on "I'm a Believer". This version, from the group's second album "More of the Monkees", stayed on the top of the chart for seven weeks in December, 1966 and became the top hit of 1967. FYI The Monkees featured the Jimi Hendrix Experience as their opening act in July 1967.

"I'm a Believer" was covered by Smash Mouth (Steve Harwell, Kevin Coleman, Greg Camp and Paul De Lislend) in 2001, as part of the soundtrack to the movie Shrek. Smash Mouth also released the song on a self-titled album.