Known for combining indie rock, pop, and classical influences into lush compositions, they released their debut album San Fermin on Downtown Records in 2013.

[1] San Fermin generally perform as an eight-piece group, pairing traditional rock instrumentation (electric guitar, keyboards, drums) with baritone saxophone, trumpet, and violin.

[2] While still in college, he assisted composer Nico Muhly, known for his work with Anohni and the Johnsons, Sufjan Stevens, and Grizzly Bear, on several film scores and operas.

[5] It features performances by 22 musicians, including vocals from Ludwig-Leone's longtime collaborator Allen Tate, as well as Jess Wolfe and Holly Laessig of Lucius.

[3] San Fermin released their lead single "Sonsick" on December 4, 2012,[6] which Pitchfork gave a positive review, declaring the song "deliriously infectious.

[4] In the months following, the line-up and size of the band shifted; by Fall 2013, the collective settled as an eight-member touring group made up of both musicians who helped record San Fermin, including Tate, trumpeter John Brandon, and saxophonist Stephen Chen, as well as newly recruited members, namely vocalist Rae Cassidy, guitarist Tyler McDiarmid, percussionist Michael Hanf, and violinist Rebekah Durham.

While Cassidy's voice and style was a departure from those of the women of Lucius on the record, her interpretations of the songs have been praised by numerous critics, including Paul Krugman of The New York Times.

[14] The New Yorker recognized the musicianship of the entire eight-piece live ensemble, noting their ability to "deliver epic and emotion-laden rock, with glorious and operatic vocals, electronic break beats, horns, strings, and other flourishes.

[32] On April 12, 2019, it was announced via San Fermin's Instagram page that vocalist Charlene Kaye was leaving the band later that month to pursue other musical opportunities.

[37] On June 26, 2019, San Fermin released the single "The Hunger" featuring vocalist Samia and announced a North American tour for Fall 2019 to support a then untitled fourth LP.

[43][44] In December 2021, San Fermin released the collaborative EP In This House, which features Attacca Quartet, Nico Muhly, Lisel (Eliza Bagg, a former touring member), Sorcha Richardson, Thao, Wye Oak, Wild Pink, and The Districts.

[49][50] Arms has a more intimate, direct sound than much of San Fermin's previous work, which Ludwig-Leone ascribed to a decision to begin with the lyrics and to write the music on the piano.

The remaining musicians included singers Holly Laessig and Jess Wolfe of Lucius, cellist Clarice Jensen, violinists Rob Moose and Caroline Shaw, and violist Nadia Sirota, among others.

These include, but are not limited to members of the ensemble yMusic, Roomful of Teeth contributors Estelí Gomez, Caroline Shaw, and Eliza Bagg, classical flutist Isabel Gleicher, trombonist Alan Ferber, and harpist Lavinia Meijer.