The Socialist Party of France (Parti socialiste de France) was founded in 1902, during a congress in Commentry, by the merger of the Marxist French Workers' Party led by Jules Guesde and the Blanquist Central Revolutionary Committee of Édouard Vaillant.
Unlike the French Socialist Party of Jean Jaurès, it refused to support "bourgeois governments" and so, to take part in the Bloc des gauches coalition. However, the two parties merged in 1905, under the pressure of the Second International, into the French Section of the Workers' International.