- Paul McCartney – vocal, bass
- John Lennon – backing vocal, rhythm guitar, organ
- George Harrison – backing vocal, lead guitar
- Ringo Starr – drums, bongos
I'm Down was written by Paul McCartney. It is a conventional, twelve-bar-blues, written in 1965 to be the b-side for the single release of Help!
The song was intentionally framed as a wild, up-tempo, hard rocker in the style of Little Richard, whom McCartney greatly admired. The track bears some resemblances to Long Tall Sally, one of Little Richard's most influential hits, and a song the Beatles frequently used as a closer for their live concerts. During their last year as a performance group, the Beatles used I'm Down as their closer instead. It was performed at Shea Stadium in 1965 before 55,600 screaming fans, where John Lennon famously played the Vox Continental organ with his elbows.
Curiously, this song was recorded on the same day as Yesterday and I've Just Seen a Face, two songs that could not be more distant from I'm Down in terms of energy level and mood. This was on June 14, 1965. Seven takes were required to set down the backing track. (Take 1 can be heard on Anthology 2.) Listen for McCartney's phrase, "Plastic soul, man, plastic soul." He later clarified that this was a term some black musicians used as a moniker for Mick Jagger. The name "Rubber Soul" arose as a morph of this idea. I'm Down never came out on a studio album, either in the UK or the US. It was released on the flip side of Help! (mono version only) in the US on July 19, 1965 and in the UK on July 23.