The Social Democratic Party of British Columbia (SDPBC) was a social democratic organisation established in May 1907 by defecting members of the impossibilist Socialist Party of Canada. Headed by pioneer Canadian socialist Ernest Burns, the SDPBC was a key constituent group behind the formation of the Social Democratic Party of Canada in 1911.
Prior to the formation of the Socialist Party of British Columbia in 1901, socialists in the Canadian province of British Columbia were split into approximately five small local groups, professing allegiance to several fledgling national organisations located outside the province. In an effort to unify these scattered forces, a unity convention was held and the Vancouver-based Socialist Party of British Columbia (SPBC) was founded.
A strong American influence marked the new organisation, reflected in the group's leading personnel and programme. Chief provincial organiser of the SPBC was Ernest Burns, formerly an activist in the Social Democratic Federation in Great Britain before moving to North America where he organised for the People's Party and the Socialist Party in Washington. The reform-oriented programme of the Socialist Party of America was adopted wholesale by the new Canadian group.
The initial moderate orientation of the SPBC proved unsatisfactory for the revolutionary socialist local organisation in Nanaimo, however, which soon broke from the SPBC to form the Revolutionary Socialist Party of Canada. Pressure was brought to bear to radicalise the party and in January 1902 at the second annual convention of the SPBC the Socialist Party of America's programme was scrapped and a new impossibilist document eliminating all "immediate demands" was adopted. A reunification of the SPBC and the Revolutionary Socialist Party followed later that same year. At the 1904 convention of the SPBC this organisation expanded its horizons, christening itself the Socialist Party of Canada (CPC), although remaining in practice a British Columbia-dominated group.