Lennon said of the song, "Paul wrote it in the Cavern days. We just stuck a few more words on it like 'grandchildren on your knee' and 'Vera, Chuck and Dave' ... this was just one that was quite a hit with us." In his 1980 interview for Playboy he said, "I would never even dream of writing a song like that."
The song was nearly released on a single as the B-side with either "Strawberry Fields Forever" or "Penny Lane" as the A-side. Instead, Martin decided on a double-A-sided-disc. The single did not make #1 in the UK, breaking a string of #1 singles going back to 1963. If "When I'm Sixty-Four" had been issued as a B-side, it would not have appeared on Sgt. Pepper.
According to Ian MacDonald, the song was "aimed chiefly at parents, and as a result got a cool reception from the [Beatles'] own generation."