The Progressive Labor Party (PLP) is an anti-revisionist Marxist–Leninist communist party in the United States. It was established in January 1962 as the Progressive Labor Movement following a split in the Communist Party USA, adopting its new name at a convention held in the spring of 1965. It was involved in the anti-Vietnam War movement of the 1960s and early 1970s through its Worker Student Alliance faction of Students for a Democratic Society.

Students for a Democratic Society (SDS) was a national student activist organization in the United States during the 1960s and was one of the principal representations of the New Left. Disdaining permanent leaders, hierarchical relationships and parliamentary procedure, the founders conceived of the organization as a broad exercise in "participatory democracy". From its launch in 1960 it grew rapidly in the course of the tumultuous decade with over 300 campus chapters and 30,000 supporters recorded nationwide by its last national convention in 1969. The organization splintered at that convention amidst rivalry between factions seeking to impose national leadership and direction, and disputing "revolutionary" positions on, among other issues, the Vietnam War and Black Power.