After deciding to produce a concept album with a story devised by Gabriel about Rael, a Puerto Rican youth from New York City who is taken on a journey of self-discovery, Genesis worked on new material at Headley Grange for three months.

The album was marked by increased tensions within the band as Gabriel, who insisted on writing all of the lyrics, temporarily left to work with filmmaker William Friedkin and needed time to be with his family.

[6] The band decided to produce a double album before they had agreed on its contents or direction, for the extended format presented the opportunity for them to put down more of their musical ideas.

[10] They had wanted to produce a concept album that told a story for some time, and Rutherford pitched an idea based on the fantasy novel The Little Prince by Antoine de Saint-Exupéry, but Gabriel considered it "too twee" and believed "prancing around in fairyland was rapidly becoming obsolete".

[11][12] Gabriel presented a surreal story about a Puerto Rican youth named Rael who is taken on a spiritual journey of self-discovery and identity as he encounters bizarre incidents and characters.

[19] In contrast to Selling England by the Pound, which contained strong English themes, Gabriel made a conscious effort to avoid repetition and instead portray American imagery in his lyrics.

[12] He had the story begin on Broadway in New York City, and makes references to Caryl Chessman, Lenny Bruce, Groucho Marx, Marshall McLuhan, Howard Hughes, Evel Knievel and the Ku Klux Klan.

[20] Gabriel expressed some concern over the album's title shortly after its release, but clarified that the lamb itself is purely symbolic and a catalyst for the peculiar events that occur.

[22] Gabriel explained that "I maintained then (and still do) that not many stories are written by committee", while Banks said that the rest of the group "felt it would give the album a bit of a one-dimensional quality and, for me, lyrically speaking, that is what happened.

[27] Gabriel was still working on the lyrics a month later, and asked the band to produce additional music for "The Carpet Crawlers" and "The Grand Parade of Lifeless Packaging" so he could fit in words that had no designated section for them.

[34] Thinking the extra material was to be instrumental, the band later found that Gabriel had sung over their new parts,[41] something that he also had done on Foxtrot and Selling England by the Pound and caused songs to be musically dense.

Fearing for his life, Rael escapes into a corridor ("The Grand Parade of Lifeless Packaging")[44] and has an extended flashback of returning from a gang raid in New York City,[45] a dream where his hairy heart is removed and shaved with a razor, ("Back in N.Y.C.")

[53] "Fly on a Windshield" came from a group improvisation sparked by Rutherford's idea of Egyptian pharaohs going down the Nile, which Hackett compared to Maurice Ravel's Boléro.

"[57] While mixing at Island Gabriel asked Brian Eno, who was working on his album Taking Tiger Mountain (By Strategy), to add synthesized effects on his vocals on several tracks, including "The Grand Parade of Lifeless Packaging".

[71] Collins remembered Hackett playing "these dark chords, then Peter blows into his oboe reeds, then there was a loud clap of thunder and we really thought we were entering another world or something.

[75] The synthesizer solo was developed as a joke, parodying traditional rock forms, but when played back the band found it sounded stronger than they had intended.

In contrast to previous Genesis album covers, which were colourful and more pastoral in nature, Hipgnosis conceived a monochrome design of a storyboard made of photographs depicting Rael in various settings from the story.

"[80] The photographs were shot on black-and-white negative, of which the prints were cut, adjusted, and touched up with several artistic processes by Richard Manning to produce a final composite.

Banks hoped the album would end people's comparisons of Genesis to Yes and Emerson, Lake & Palmer, two other popular progressive rock bands of the time.

[93] In giving an interview to Melody Maker in October 1974, shortly before the album's release, Gabriel played several tracks from The Lamb to reporter Chris Welch, including "In the Cage", "Hairless Heart", "Carpet Crawlers", and "Counting Out Time".

[17] Welch's review for Melody Maker published a month later included his thoughts on such long concept albums–"A few golden miraculous notes and some choice pithy words are worth all the clutter and verbiage"–and he called the album a "white elephant".

She summarised The Lamb as a combination of the "musical proficiency" on Selling England by the Pound (1973) with the "grandiose illusions" on Foxtrot (1972) and "a culmination of past elements injected with present abilities and future directions".

[94] Colin Irwin wrote a negative review of the "Counting Out Time" single, with its "weary, tepid approach" and a "woeful, dreary three and a half minutes".

A remastered edition for Super Audio CD and DVD with new stereo and 5.1 surround sound mixes by Nick Davis was released in 2008 as part of the Genesis 1970–1975 box set.

Also included is a 60-page book, featuring notes by Alexis Petridis, a band member commentary and "rare images", and a 1975 tour programme, poster and replica ticket.

[111] 29 October 1974 was to begin an 11-date tour of the UK that sold out within four hours, but after Hackett crushed a wine glass in his left hand which severed a tendon, and needed time to recover, these dates were rescheduled for 1975.

[43] Even on those occasions when Gabriel's mouth reached the microphone, and he did not get stuck coming out of the tube or trip and fall due to the poor visibility, he was too out of breath from his struggles with the costume to sing properly.

[109] Between the end of "In the Rapids" and the start of "It", an explosion set off twin strobe lights that revealed Gabriel and a dummy figure dressed identically on each side of the stage, leaving the audience clueless as to which was real.

[113] In one concert review, the theatrics for "The Musical Box", the show's encore and once the band's stage highlight, was seen as "crude and elementary" compared to the "sublime grandeur" of The Lamb...

[108] The decision was kept a secret from outsiders and media all through the tour, and Gabriel promised the band to stay silent about it for a while after its end in June 1975, to give them some time to prepare for a future without him.