The Federation of the Socialist Workers of France (French: Fédération des travailleurs socialistes de France, FTSF) was France's first socialist party, being founded in 1879.^[1]

The party was characterised as possibilist because it promoted gradual reforms.^[2]

After the failure of the Paris commune (1871), French socialism was beheaded as its leaders were dead or exiled. During the Marseille Congress (1879), workers' associations created the Federation of the Socialist Workers' Party of France (Fédération du parti des travailleurs socialistes de France), but in 1882 Jules Guesde and Paul Lafargue (the son-in-law of Karl Marx) left the federation which they considered too moderate and founded the French Workers' Party (Parti ouvrier français, POF). The Federation, initially renamed the Revolutionary Socialist Labour Party (Parti ouvrier socialiste révolutionnaire), and then commonly the Federation of the Socialist Workers of France (Fédération des travailleurs socialistes de France, FTSF), led by Paul Brousse was defined as possibilist because it advocated gradual reforms whereas the POF promoted Marxism. At the same time, Édouard Vaillant and the heirs of Louis Auguste Blanqui founded the Central Revolutionary Committee (Comité révolutionnaire central, CRC), which represented the French revolutionary tradition.

In the 1880s, the socialists knew their first electoral success, conquering some municipalities. Jean Allemane and some FTSF members criticized the focus on electoral goals. In 1890, they split and created the Revolutionary Socialist Workers' Party (Parti ouvrier socialiste révolutionnaire, POSR), which advocated the revolutionary general strike. Additionally, some deputies identified as socialists without being members of any party. These mostly advocated moderation and reform.

While the Dreyfus Affair divided the country in the 1890s, socialist organizations debated whether to ally with other left-wing forces in defense of Alfred Dreyfus and against nationalism and clericalism. Contrary to Jean Jaurès, Jules Guesde thought the socialists should not ally with groups supporting bourgeois democracy. In 1899, a debate raged among socialist groups about the participation of Alexandre Millerand in Pierre Waldeck-Rousseau's cabinet, which included the Marquis de Gallifet, best known for having directed the bloody repression during the Paris Commune. In 1902, the FTSF, the POSR and Jaurès's followers merged into the French Socialist Party. This one merged three years later with the Socialist Party of France of Guesde in the French Section of the Workers' International.

• French Section of the Workers' International
• French Socialist Party
• History of communism
• History of socialism
• History of the Left in France