American student organization that flourished in the mid-to-late 1960s and was known for its activism against the Vietnam War.

SDS, founded in 1959, had its origins in the student branch of the League for Industrial Democracy, a social-democratic educational organization. An organizational meeting was held in Ann Arbor, Mich., in 1960, and Robert Alan Haber was elected president of SDS. Initially SDS chapters throughout the nation were involved in the civil rights movement. Operating under the principles of the “Port Huron Statement,” a manifesto written by Tom Hayden and Haber and issued in 1962, the organization grew slowly until the escalation of U.S. involvement in Vietnam (Vietnam War) (1965). SDS organized a national march on Washington, D.C., in April 1965, and, from about that period, SDS grew increasingly militant, especially about issues relating to the war, such as the drafting of students. Tactics included the occupation of university and college administration buildings on campuses across the country. By 1969 the organization had split into several factions, the most notorious of which was the “Weathermen,” or “Weather Underground,” which employed terrorist tactics in its activities. Other factions turned their attention to the Third World or to the efforts of black revolutionaries. Increasing factionalism within the ranks of SDS and the winding down of the Vietnam War were but two of the reasons for the dissolution of SDS. By the mid-1970s the organization was defunct.