Caldwell was born in Maryville, Missouri, and grew up in Fayetteville, Arkansas. She was a child prodigy and gave public performances on the violin by the time she was ten years old. She graduated from Fayetteville High School at the age of 14.
Caldwell graduated from Hendrix College in 1944 and attended the University of Arkansas as well as the New England Conservatory of Music. She won a scholarship as a viola player at the Berkshire Music Center in 1946. In 1947, she staged Vaughan Williams's Riders to the Sea. For 11 years she served as the chief assistant to Boris Goldovsky.
Caldwell moved to Boston, Massachusetts, in 1952 and became head of the Boston University opera workshop. In 1957 she started the Boston Opera Group, which became the Opera Company of Boston, where she staged a wide range of operas, establishing a reputation for producing difficult works under pressure. She was also known for putting together interesting variations on standard operas. Highlights in Boston that she conducted and/or stage directed included La voyage de la lune, Otello (with Tito Gobbi as Iago), Command Performance (world premiere), Manon and Faust (both with Beverly Sills and Norman Treigle), Lulu (U.S. East Coast premiere), I puritani (with Dame Joan Sutherland), Intolleranza (U.S. premiere), Boris Godunov (original version), Hippolyte et Aricie (U.S. stage premiere, with Plácido Domingo), La bohème (with Renata Tebaldi and Domingo), Moses und Aron (U.S. premiere), The Rake's Progress, Bluebeard's Castle, Carmen (with Marilyn Horne), Macbeth (original version), The Good Soldier Schweik, The Fisherman and His Wife (world premiere, with Muriel Costa-Greenspon), La finta giardiniera, Norma (with Sills), Les Troyens, Don Carlos (U.S. premiere of original French version), Don Quichotte, War and Peace (U.S. stage premiere, with Arlene Saunders), Benvenuto Cellini (U.S. premiere, with Jon Vickers), I Capuleti e i Montecchi, Montezuma (U.S. premiere), Ruslan and Ludmila (U.S. premiere), Rigoletto (with Sills, Richard Fredricks, and Susanne Marsee), Stiffelio (U.S. stage premiere), La damnation de Faust, Tosca (with Magda Olivero), La vide breve, El retablo de maese Pedro, The Ice Break (U.S. premiere), Aïda (with Shirley Verrett in the title role), Die Soldaten (U.S. premiere), The Invisible City of Kitezh, Taverner (U.S. premiere), The Makropoulos Case (with Anja Silja, William Cochran, and Chester Ludgin), Médée (in French and Greek), Dead Souls (U.S. premiere), Der Rosenkavalier (with Dame Gwyneth Jones) and, finally, The Balcony (world premiere, 1990).
At the New York City Opera, Caldwell staged Der junge Lord and Ariadne auf Naxos (with Carol Neblett), both in 1973. In 1976, she both conducted and directed Il barbiere di Siviglia (with Sills and Alan Titus), which was televised over PBS, and did the same for Falstaff (with Donald Gramm) in 1979.
In 1976, Caldwell became the first female conductor at the Metropolitan Opera, with La traviata (with Sills). In 1978, she led L'elisir d'amore there, with José Carreras and Judith Blegen. She appeared with the New York Philharmonic, the Pittsburgh Symphony Orchestra, the St. Paul Chamber Orchestra, and the Boston Symphony Orchestra.
Also in 1976 she directed John La Montaine's U.S. Bicentennial opera Be Glad Then, America with Odetta (Muse for America), Donald Gramm (various patriots), Richard Lewis (King George III), David Lloyd (Town Crier), and the Penn State University Choirs and the Pittsburgh Symphony.
Caldwell also directed one non-musical production, the 1981 Lincoln Center staging of Shakespeare's Macbeth, presented on cable TV in 1982. It starred Philip Anglim and Maureen Anderman, with a then-unknown Kelsey Grammer in the supporting role of Ross.
In the 1980s, Opera New England, a branch of Ms. Caldwell's Opera Company of Boston, was the touring ambassador of opera to the New England states. She employed young professional singers in productions that were fully staged and with orchestra. She organized financing through local, state and federal funding which included the National Endowment for the Arts, Massachusetts Council of the Arts & Humanities, Connecticut Commission on the Arts, New Hampshire Commission of the Arts and the Maine Commission on the Arts & Humanities.
- Donizetti: Don Pasquale (Sills, Kraus, Titus, Gramm; Caldwell, 1978) EMI
- Rossini: Il barbiere di Siviglia (Sills, H.Price, Titus, Gramm, Ramey; Caldwell, Caldwell, 1976) [live]
- Learn everything you can, anytime you can, from anyone you can - there will always come a time when you will be grateful you did.
- If you approach an opera as though it were something that always went a certain way, that's what you get. I approach an opera as though I didn't know it.
- If you can sell green toothpaste in this country, you can sell opera.
- Challenges: A Memoir of My Life in Opera, by Sarah Caldwell (with Rebecca Matlock), Wesleyan University Press, 2008. ISBN 0-8195-6885-6
- Sarah Caldwell: The First Woman of Opera, by Daniel Kessler, The Scarecrow Press, Inc, 2008. ISBN 978-0-8108-6110-7
- The Boston Opera Company 1909-1915, by Quaintance Eaton, Appleton-Century Press, (1965) New York.
- G. W. Bowersock (March 2009). "Beverly Sills Greenough 25 May 1929 · 2 July 2007". Proceedings of the American Philosophical Society. 153 (1). Retrieved 2015-01-05.
- "Chinatown/South Cove". Boston Women's Heritage Trail.
- on YouTube, with Beverly Sills (1976).
- Sarah Caldwell, impresario of Boston opera, dead at 82 -- The Boston Globe
- Sarah Caldwell, Indomitable Director of the Opera Company of Boston, Dies at 82 -- The New York Times
- Memorial Service for Sarah Caldwell
- Time Magazine November 10, 1975, cover article
- Sarah Caldwell interview by Bruce Duffie, 1992