The songwriting credit Lennon-McCartney appears on all Beatles songs that were written by John Lennon and/or Paul McCartney, thanks to a mutual agreement which they made in the band's early days. As a result, royalties were shared equally between the two. To date, it is one of the best known songwriting partnerships.

On the Beatles' first album Please Please Me the partnership appears as McCartney-Lennon, in all later albums Lennon's name comes first.

In practice, almost all of the later Lennon-McCartney songs were written by one or the other rather than both, although each would contribute ideas during the arrangement and recording of songs. "A Day in the Life" is one of the only later Beatles song that actually includes substantial contributions by both Lennon and McCartney, and only then because part of a separate song by McCartney was used to flesh out the middle of Lennon's composition.

In the 1990s & early 21st century, Paul McCartney attempted to have the credits reversed to McCartney-Lennon for a number of songs which he wrote, most notably "Yesterday", but this was opposed by Lennon's estate. In a February 2005 statement, however, he stated that, "...it’s something that I don’t have a problem with anymore."