The song was written by the Bar-Kays while they were rehearsing with Norman West to perform a cover of J. J. Jackson's "But It's Alright".
[1] It begins with the melody of the popular children's song "Mary Had a Little Lamb" and then cuts into the main riff, punctuated with a high trumpet trill.
It features a chorus of neighborhood children who had been loitering outside the recording studio; they were instructed to shout "Soul Finger!"
[1] The idea for the title and the shouts came from the Stax songwriters Isaac Hayes and David Porter.
[1] The track was used as the opening theme tune to BBC Radio 1 DJ Stuart Henry's shows from 1969 to 1974.