"We Can Work It Out" is a song written by John Lennon and Paul McCartney and released by The Beatles as a "double A-sided" single with "Day Tripper", the first time both sides of a single were so designated in an initial release. Both songs were recorded during the Rubber Soulsessions. The song is an example of Lennon/McCartney collaboration at a depth that happened only rarely after they wrote the hit singles of 1963. This song, "A Day in the Life", and "I've Got A Feeling" are among the notable exceptions.

McCartney wrote the words and music to the verses and the chorus, with lyrics that "might have been personal" and thus a reference to his relationship with Jane Asher. McCartney then took the song to Lennon: "I took it to John to finish it off and we wrote the middle together." According to Lennon, he "did the middle eight."

With its intimations of mortality, Lennon's contribution to the twelve-bar bridge contrasts typically with what Lennon saw as McCartney's cajoling optimism. As Lennon told Playboyin 1980, "You've got Paul writing, 'We can work it out / We can work it out'—real optimistic, y'know, and me, impatient: 'Life is very short, and there's no time / For fussing and fighting, my friend.'" Based on those comments, some critics overemphasized McCartney's optimism, neglecting the toughness in passages written by McCartney, such as "Do I have to keep on talking until I can't go on?". Lennon's middle shifts focus from McCartney's concrete reality to a philosophical perspective in B minor, illustrating this with a waltz-time section suggested by George Harrison that leads back to the verse, possibly meant to suggest tiresome struggle. Music critic Ian MacDonald said, "[Lennon's] passages are so suited to his Salvation Army harmonium that it's hard to imagine them not being composed on it. The swell-pedal crescendos he adds to the verses are, on the other hand, textural washes added in the studio, the first of their kind on a Beatles record and signposts to the enriched sound-palette of Revolver." Oasis guitarist Noel Gallagher described the song as "the song that defines The Beatles".

The Beatles recorded "We Can Work It Out" on 20 October 1965, four days after its accompanying single track, with an overdub session on 29 October. They spent nearly 11 hours on the song, by far the longest expenditure of studio time up to that point.

In a discussion about what song to release as a single, Lennon argued "vociferously" for "Day Tripper", differing with the majority view that "We Can Work It Out" was a more commercial song. As a result, the single was marketed as the first "double A-side," but airplay and point-of-sale requests soon proved "We Can Work It Out" to be more popular, and it reached No. 1 on both sides of the Atlantic, The Beatles' fastest-selling single since "Can't Buy Me Love," their previous McCartney-led A-side in the UK.

"We Can Work It Out" was the last of six number one singles in a row on the American charts, a record at the time. It was preceded by "I Feel Fine", "Eight Days a Week", "Ticket to Ride", "Help!", and "Yesterday". The record was equaled by The Bee Gees in the 1970s and surpassed by Whitney Houston in the 1980s.

The Beatles made 10 black-and-white promo films for television broadcasters on 23 November 1965, at Twickenham Film Studios in London, as they were often unable to make personal appearances by that time. Three of the films were mimed performances of "We Can Work It Out", in all of which Lennon was seated at a harmonium. The most frequently-broadcast of the three versions was a straightforward performance piece with the group wearing black suits. Another had the group wearing the stage suits from their Shea Stadium performance on 15 August; the third opens with a shot of Lennon with a sunflower in front of his eye.

In 1991, McCartney played an acoustic version of the song for his MTV Unplugged performance, memorable for his flubbing the first verse and his good-natured reaction, later released on Unplugged (The Official Bootleg).

MacDonald was not sure whether or not Harrison sang a harmony vocal part. MacDonald praised the tambourine playing and noted that some sources attribute it to Harrison, not Starr.