Maoist
Freedom Road Socialist Organization, Maoist Internationalist Movement, Revolutionary Worker/ Revolutionary Communist Part
Trotskyist
Freedom Socialist Party, Socialist Action, Socialist Viewpoint, Solidarity, The Workers League and the Socialist Equality Part
International Socialist Organization
Publishes the newspaper Socialist Worker and the magazine International Socialist Review.
Socialist Alternative
Revolutionary Marxist organization, US section of the Committee for a Workers International (CWI). Formerly Labor Militant. Publishes "Justice" newspaper.
Workers World online
Under the leadership of Sam Marcy, this group split from the Socialist Workers Party (US) in the late 1950s over the latter's condemnation of the Soviet invasion of Hungary. The website includes a news service and various writings by Marcy.
World Socialist Party of the USA
Renounces violence, Soviet-style totalitarianism, money and all forms of leadership. They advocate a classless, "wageless, moneyless, free access society" without any national borders. Marxist but not Leninist.