“Join Together” came out of a project that never got finished. Pete Townshend spent much of 1970 and 1971 building Lifehouse, a science-fiction rock opera meant to exist as an album, a stage show, and a series of real-life participatory concerts at once. The ambition collapsed under its own weight, and Townshend suffered a breakdown trying to hold it together. What survived were songs, some of which became Who's Next, and others that The Who released as standalone singles over the following two years. “Join Together” was one of three such Lifehouse castoffs, alongside “Let's See Action” and “Relay,” none of which appeared on a studio album at the time.

Roger Daltrey has told a version of the song's origin that makes it sound almost accidental. “I remember when Pete came up with ‘Join Together.’ He literally wrote it the night before we recorded it,” Daltrey recalled. The band cut it on May 22, 1972, at Olympic Studios in London. That account sits awkwardly next to the Lifehouse Chronicles box set, released in 2000, which includes an earlier demo of the song that points to a longer gestation reaching back toward the original Lifehouse sessions. Both things can be true. Townshend may have been refining an old fragment for over a year and still have finished the version that mattered in a single night.

The song's most distinct feature is its synthesizer line, built on an ARP that Townshend had been teaching himself to program at home, the same unit he later used on “Who Are You?” He set it against a Lowrey Berkshire TBO-1 organ, the instrument already heard driving “Baba O'Riley” and “Won't Get Fooled Again.” A chord harmonica and a bass harmonica filled the bridge, the bass part played by John Entwistle. The arrangement put The Who's guitar-and-power-chord identity through a kind of test, swapping the instrument most associated with the band for circuitry Townshend was still learning to control.

Daltrey was not quiet about his doubts. He has said he worried the band would spend its time chasing “piddly one-note noises” that a guitar could have produced more directly, and that he did not think Townshend's sequencing work did much the guitar couldn't already do. The irony is that The Who had already leaned into synthesizers on “Baba O'Riley” and “Won't Get Fooled Again” by the time Daltrey raised the complaint, and the band would keep using them through “Who Are You,” “You Better You Bet,” and “Eminence Front” later in the decade.

Released as a non-album single on June 16, 1972, on Track Records in the UK and Decca in the US, “Join Together” reached number 9 on the UK chart and number 17 on the Billboard Hot 100. Its B-side carried a live, unedited recording of Marvin Gaye's “Baby Don't You Do It,” taped at a December 1971 show in San Francisco. The promotional film, shot that June, shows Townshend and Daltrey performing with their hands wrapped in bandages, and it premiered on American Bandstand that December. The song stayed in the band's live rotation for years, worked into a blues jam attached to “My Generation” through the mid-1970s tours, and brought back in 2011 for the Concert for Killing Cancer alongside Debbie Harry and Jeff Beck. A 2008 Nissan Maxima commercial gave it a different kind of afterlife, the synthesizer riff that once worried Daltrey now just another familiar sound from a band that had long since made peace with it.