21

Adele started writing 21 in April 2009, aiming for something more upbeat than 19, but the early sessions produced only Take It All, produced by Jim Abbiss. When the relationship ended she changed course. Within a day she called Paul Epworth: she had argued with her partner the night before, she said, and then went into the studio and screamed. Fraser T Smith turned her demo of Set Fire to the Rain into the finished track, with live drums and strings arranged by Rosie Danvers. Ryan Tedder wrote the opening piano of Turning Tables and arrived four hours early to their first session. Rumour Has It was written and recorded at Serenity West in Los Angeles, and she sang its main vocals in ten minutes.

Rick Rubin had been signed as sole producer and re-recorded the demos at Shangri-La Studio in Malibu in April 2010 with Chris Dave on drums, James Poyser on piano and Pino Palladino on bass. She was unhappy with much of it and kept the early takes. Don't You Remember, He Won't Go, One and Only and the bonus track I Found a Boy come from the Rubin sessions. Someone Like You came weeks later, as voice and piano. She first meant to call the album after Rolling in the Deep, then chose 21, her age while she wrote.

On her 2008-09 North American tour a Nashville-born bus driver introduced her to bluegrass, rockabilly and country, music she said she had not grown up around. She later called it a break-up record. It debuted at number one in the UK on 30 January 2011 with 208,000 copies, spent 23 weeks at the top there and 24 weeks at number one in the United States, and was the world's best-selling album of both 2011 and 2012. Pitchfork's Dani Blum wrote in 2020 that it cemented her legacy as an artist who could make once-in-a-generation milestones out of her music. In the Guardian, Will Dean called it a progressive, grown-up second collection. At the 54th Grammys on 12 February 2012 it won Album of the Year and Best Pop Vocal Album, and Epworth won Producer of the Year. Rolling Stone placed it 137th in its 2020 list of the 500 greatest albums, and it appears in the book 1001 Albums You Must Hear Before You Die.