McCartney recalls writing "For No One" in the bathroom of a ski resort in the Swiss Alps while on holiday with his then girlfriend Jane Asher. He said, "I suspect it was about another argument." The lyrics end enigmatically with "...a love that should have lasted years..." The song's working title was "Why Did It Die?" It is built upon a descending scale progression with a refrain that modulates to the supertonic minor.
The French horn solo was by Alan Civil, a British horn player described by recording engineerGeoff Emerick as the "best horn player in London". During the session, McCartney pushed Civil to play a note that was beyond the usual range of the instrument. According to Emerick, the result was the "performance of his life." Civil said that the song was "recorded in rather bad musical style, in that it was 'in the cracks' neither B-flat nor B-major. This posed a certain difficulty in tuning my instrument."