"When I'm Sixty-Four" is a song by the English rock band the Beatles, written by Paul McCartney (credited to Lennon-McCartney) and released on their 1967 album Sgt. Pepper's Lonely Hearts Club Band. It was one of the first songs written by McCartney, who wrote it when he was 16. The song was recorded in a different key than the final recording; it was sped up at the request of McCartney to make his voice sound younger. It prominently features a trio of clarinets (two regular clarinets and one bass clarinet) throughout.