The group was founded by two dissident factions which had emerged at the Socialist Workers Party's 1971 convention.
Their initial criticism of the SWP was that it focused too much on the feminist, peace and "nationalist" movements, rather than the proletariat.
After being expelled after the convention some members joined with the Vanguard Newsletter group, while others entered the International Socialists.
They left the RSL in early 1974 and "retain[ed] a degenerated workers' state analysis".
[3] On April 20, 1973 the Leninist faction held a fusion conference with Vanguard Newsletter group to form the Class Struggle League.