Joan Baez was born on Staten Island, New York, to a Quaker family of Mexican, English and Scottish descent. Her father Albert Baez, a physicist, refused lucrative defense industry jobs, probably influencing Joan's political activism in the American and international civil rights and peace movements of the 1960s to the present. The family, frequently having to move by reason of his work, lived in different towns across the United States, in France, Switzerland, Italy, and the Middle East, where they stayed in 1951. Baez, at the time only ten years old, was deeply influenced by the poverty and the inhuman treatment the local population in Baghdad suffered.

In the late 1950s, Dr. Baez accepted a faculty position at MIT, and moved his family to the Boston area, at the time the center of the up-and-coming folk music scene, and Joan began performing locally in Boston/Cambridge area clubs, and attended Boston University. Her most noted venue was the Club 47 Mount Auburn, in Cambridge, where she performed twice a week for $20 per show. It was with other performers from the same club that she recorded her first album, Folksingers 'Round Harvard Square.

Baez's true professional career began at the 1959 Newport Folk Festival and she recorded "Joan Baez", her first album for a major company, the following year on Vanguard Records. The collection of traditional folk ballads, blues and laments sung to her own guitar accompaniment sold moderately well. Her second release, Joan Baez, Vol. 2 in 1961 went gold, as did, Joan Baez in Concert, parts 1 and 2 (released in 1962 and 1963, respectively). From the early to mid-1960s, Baez emerged at the forefront of the American roots revival, where she introduced her audiences to the less prominent Bob Dylan (the two became romantically involved in late 1962, remaining together through early 1965), and was emulated by artists such as Joni Mitchell and Bonnie Raitt.

During this period, as the Vietnam War and the Civil Rights struggle in America both became more prominent issues, Baez focused more of her attention on both areas, until eventually her music and her political involvement became inseparable. Her performance of "We Shall Overcome" at Martin Luther King's March on Washington permanently linked her with the anthem, and was frequently highly visible in civil rights marches.

Her performance of "I dreamed I saw Joe Hill" is also anthological. She also became more vocal about her disagreement with the U.S. war in Vietnam, publicly disclosing that she was withholding sixty percent of her income taxes (as that was the figure commonly determined to fund the military), and encouraging draft resistance at her concerts. In 1965 she founded the Institute for the Study of Nonviolence.

Like Dylan, Baez was profoundly influenced by the British Invasion and began augmenting her acoustic guitar on 1965s Farewell Angelina just after Dylan began experimenting with folk-rock. Later in the decade, Baez experimented with poetry (1968s Baptism: A Journey Through Our Time) and country music (1969s David's Album and 1970s One Day at a Time).

In 1968, Baez married David Harris, a prominent anti-Vietnam War protester eventually imprisoned for draft evasion. The couple divorced in 1973. Harris, a country music fan, turned Baez toward more complex country rock influences beginning with David's Album. In 1969, Baez' appearance at the historic Woodstock music festival in upstate New York afforded her an international musical and political podium, particularly upon the successful release of the like-titled documentary film. Her 1971 cover of The Night They Drove Old Dixie Down (by The Band) was a top 10 hit in the United States.

Meanwhile, Baez' political involvement had by no means ceased. During Christmas of 1972, she joined a peace delegation traveling to North Vietnam, both to address human rights in the region, as well as to deliver Christmas mail to American POW's. During her time there, she was caught in the U.S. military's "Christmas bombing" of Hanoi, during which the city was bombed for eleven straight days.

She also devoted a substantial amount of her time in the early 1970s to helping establish a U.S. branch of Amnesty International, and has since worked on improving human rights, both in Latin America and Southeast Asia. Her disquiet at the human rights violations of communist Vietnam made her increasingly critical of its government and she organized the publication, on May 30, 1979, of a full-page advertisment, published in four major U.S. newspapers, in which the communists were described as having created a nightmare (which put her at odds with a large segment of the domestic left wing, who were uncomfortable criticizing a leftist regime).

This experience ultimately led Baez to found her own human rights group, Humanitas International, whose focus was to target oppression wherever it occurred, criticizing right and left wing regimes equally. She toured Chile, Brazil and Argentina in 1981, but was prevented from performing in any of the three countries, fearful her criticism of their human rights practices would reach mass audiences, if she were given a podium. (A film of the ill-fated tour, There but for Fortune, was shown on PBS in 1982.)

With 1972s Come from the Shadows, Baez switched to A&M Records, flirting with mainstream pop music as well as writing her own songs for her best-selling 1975 release Diamonds & Rust. She switched to CBS Records briefly during the late 1970s, but found herself without an American label for the release of 1984s Live -Europe '83.

She didn't have an American release until 1987's Recently on Gold Castle Records, and then switched to Virgin Records for 1992s Play Me Backwards. Her 2003 album, Dark Chords on a Big Guitar, found her performing songs by composers half her age, while a November 2004 performance at New York's Bowery Ballroom was recorded for a 2005 live release, Bowery Songs.

Baez played a significant role in the 1985 Live Aid concert for African famine relief, opening the U.S. segment of the show in Philadelphia. She also has toured on behalf of many other causes, including Amnesty International's 1986 A Conspiracy of Hope Tour and a guest spot on their subsequent Human Rights Now! Tour.

Baez toured with Bob Dylan in 1964 and 1965, during his 1975 and 1976 Rolling Thunder Revue tours, and, abortively, in Europe in 1984. At one time she was romantically linked to Steve Jobs.

In August 2005, Baez appeared at the Texas anti-war protest that had been started by Cindy Sheehan. The following month, she sang "Amazing Grace" at the Temple in Black Rock City during the annual Burning Man festival as part of a tribute to New Orleans and the victims of Hurricane Katrina.

In December 2005, Baez appeared at the California protest against the execution of Tookie Williams. There, she sang "Swing Low, Sweet Chariot."

On January 13th, 2006, Baez performed at the funeral of singing legend Lou Rawls, where she led Jesse Jackson, Stevie Wonder, and others in the singing of "Amazing Grace."

Joan Baez has a son, Gabriel Harris. She was one of three sisters, her older sister being Pauline Baez; her younger sister was singer, guitarist and activist Mimi Fariña, born Margarita Mimi Baez (1945-2001), who died of neuroendocrine cancer. The mathematical physicist and Usenet guru, John C. Baez (b. 1961), is her cousin. She is a resident of Woodside, California, and is a graduate of Palo Alto High School.