"[3] The Socialist Caucus was founded in early 1998 in Toronto by Barry Weisleder, Joe Flexer, Sean Cain, Jorge Hurtado and other political activists who had been involved in Peter Kormos's unsuccessful 1996 campaign to lead the Ontario New Democratic Party.

[5][6][7] The group is a socialist faction and advocates economic democracy and workers' control, full employment, the nationalization of large industries and the eradication of poverty and homelessness.

[11] In the 2012 and 2017 NDP leadership elections, the Socialist Caucus endorsed Niki Ashton, on the latter occasion after leading an unsuccessful effort to draft former Ontario Federation of Labour president Sid Ryan as a candidate.

[12][13] In 2011, the Socialist Caucus proposed resolutions at that year's federal NDP convention to oppose the Alberta oil sands, legalize marijuana, boycott "apartheid Israel", repeal the Clarity Act, and nationalize auto, bank and insurance companies.

The Socialist Caucus publishes a newspaper named Turn Left, edited by Sean Cain, for each federal and Ontario provincial NDP convention.

[16] The Socialist Caucus opposed resolutions at the 2011 and 2013 federal NDP conventions to rewrite the preamble of the party's constitution in order to remove its commitment to socialism.

"[19] Subsequently, the Socialist Caucus called for the removal of Mulcair as party leader and supported a leadership review at the NDP convention held in April 2016 in Edmonton.