Folk singer Pete Seeger, who established the music as an expression of community, conscience and social justice during a career that spanned eight decades, has died. He was 94.

Perhaps more than any performer, Seeger was instrumental in popularizing the traditional American folk repertoire. Many of the country's most loved songs were passed along via Seeger's voluminous recordings of them; his album discography runs to over 100 titles.

He viewed the sharing of folk songs as a democratic act. To participate in singing songs together - which Seeger encouraged in the group sing-alongs that were an inevitable feature of his concerts - was to participate in the inner workings of the country itself.

The banjo-plucking tenor's name was synonymous with musical activism from the very beginning. Reared in the leftist folk movement of the 1940s, where he appeared alongside such iconic figures as Woody Guthrie, he established himself as a member of the Almanac Singers, a group with deep ties to the U.S. labor movement.

Seeger was briefly a major pop star in the early 1950s: His quartet the Weavers recorded a slickly produced version of Lead Belly's "Goodnight Irene" that rivaled Patti Page's "The Tennessee Waltz" as the biggest single of 1950.

But Seeger's career ran aground during the anti-Communist ferment of the era. A former member of the American Communist Party, he refused to answer questions during an appearance before the House Un-American Activities Committee, resulting in a conviction for contempt of Congress that derailed him professionally and left him banned from network TV for more than a decade.

Nonetheless, he was an idol of the nascent folk revival of the '60s; his compositions "Where Have All the Flowers Gone," "If I Had a Hammer" and "Turn, Turn, Turn" were respectively recorded by the Kingston Trio, Peter, Paul & Mary and the Byrds with great commercial success.

He was closely identified with the '60s civil rights movement, and had a hand in adapting the 1901 Baptist hymn "I'll Overcome Someday" into the anthem "We Shall Overcome," which he helped popularize on a like-titled 1963 live album. He was also vocal in his endorsement of nuclear disarmament, an end to the Vietnam War and environmental protection and his opposition to capital punishment.

An enduring icon of the folk community, his music and philosophy have been embraced by generations of artists, including such performers as Bob Dylan (whose original songs were first championed by Seeger) and Bruce Springsteen (who paid homage with "We Shall Overcome: The Seeger Sessions," a 2006 recital of his material.

Springsteen later defined Seeger's import for the New Yorker's Alec Wilkinson: "He had a real sense of the musician as historical entity -- of being a link in the thread of people who sing in others' voices and carry the tradition forward…(and a sense) that songs were tools, and, without sounding too pretentious, righteous implements when connected to historical consciousness."

Seeger was born May 3, 1919, in New York. His parents were Harvard-educated musicologist (and pacificist) Charles Seeger and concert violinist and educator Constance Edson Seeger. When he turned seven, his parents divorced, and his father soon married his student, composer Ruth Crawford Seeger.

His half-siblings from that second union included the future folk singers Mike Seeger, co-founder of the New Lost City Ramblers, and Peggy Seeger, who married British folk star Ewan MacColl.

Seeger took up the ukulele as a boarding school student. He began playing the banjo after hearing folklorist Bascom Lamar Lunsford at a 1936 folk festival in North Carolina. (He would later become adept at six- and 12-string guitar and recorder).

By the time he enrolled at Harvard, Seeger was reading leftist literature like the magazine New Masses and the muckraking journalists Lincoln Steffens and Mike Gold. He joined the Young Communist League in 1936. After dropping out of Harvard in 1938, he got his first semi-professional musical experience as a member of a touring puppet theater.

In 1940, he got a job in Washington, D.C. as an assistant to a family friend, folklorist Alan Lomax, head of the Library of Congress' Archive of American Folk Song. That year, through Lomax, he met Oklahoma-born singer-songwriter Guthrie at a benefit concert for migrant workers. He was soon traveling with Guthrie, and performed with him on "Back Where I Come From," the weekly CBS Radio folk show produced by Lomax.

In 1941, Seeger became a founding member of the Almanac Singers, a politically charged folk unit whose free-floating membership also included his New York roommates, writer-musician Millard Lampell and Arkansas-born singer Lee Hays, as well as Lomax's sister Bess Lomax Hawes and Guthrie. The group recorded for Keynote Records, and was closely identified with pro-union activities and, initially, with anti-war sentiments. (The group changed its tune after Germany's invasion of Russia.)

In 1942 - the same year he joined the American Communist Party - Seeger was drafted into the wartime Army; the following year, he married Japanese-American Toshi-Aline Ohta. The couple's first child, also named Peter, died while Seeger was stationed overseas.

Following his return from the service, Seeger was instrumental in the founding of People's Songs, a group devoted to the dissemination of pro-labor material and new compositions. Hays and singer Ronnie Gilbert were present at the group's first meeting, and another singer-songwriter, Fred Hellerman, was soon contributing songs to its monthly bulletins (which served as a basis for such later folk magazines as Sing Out! and Broadside, in which Seeger was also active).

In 1948, Seeger published the first edition of his book "How to Play the 5-String Banjo," still a basic text today.