[1] It was formed in the aftermath of a fall 1961 split in the Communist Party of the United States (CPUSA) that saw the expulsion of left-wing labor activists Milt Rosen (1926–2011) and Mortimer Scheer.

[3] Rosen delivered a political report to the Cuban Revolution-inspired group urging the establishment of a new communist party in the United States to replace the CPUSA, which was characterized as irredeemably "revisionist".

[3] Rosen again delivered the main political report to the gathering, calling for the writing of a program and development of a network of clubs and affiliated mass organizations in order to win supporters for a new revolutionary socialist movement.

The PLP formally existed as a publishing partnership listing Milt Rosen and the party's 1965 candidate for New York State Senate, Bill Epton, as partners.

[8] The PLP made extensive use of mass organizations (front groups) from its earliest years, through which it spread its ideas, raised funds and recruited new members.

[9] The PLP ended its previous political line supporting the Cultural Revolution and broke with the People's Republic of China in the spring of 1971 with the publication of an internal discussion bulletin for party members detailing eight points of disagreement with the Chinese regime.

[11] The organization made use of aggressive direct action tactics against its perceived opponents, disrupting presentations by the controversial psychologist Arthur Jensen and the physicist William Shockley in the spring of 1976.

The organization picketed in Harvard Square and handed out flyers calling for demonstrations against sociobiology, which in their view was being used to defend individuals and groups responsible for racism, war, and genocide.

[6] Owing in part to the significant economic and extensive time requirements expected of its members, the PLP has since its inception been a small cadre organization, with an "estimated hard-core membership" of about 350 in 1970, supplemented by numerous sympathizers.

[14] Members during the 1960s were predominantly from white, middle-class backgrounds, shunned drug use, and tended "to dress neatly and wear short hair", according to a 1971 House Internal Security Committee staff report.