Written by Mick Jagger and Keith Richards, "She's a Rainbow" was recorded on May 18, 1967. It is most famous for its vibrant piano by Nicky Hopkins, Brian Jones' use of the mellotron, and its rich lyricism by Jagger.

John Paul Jones, later of Led Zeppelin, arranged the strings of this song during his session days. Despite rumours to the contrary, none of The Beatles perform on this track. Backing vocals were provided by Richards, Jagger, Jones and Bill Wyman.