The labor movement in Spain began in Catalonia in the 1830s and 1840s, although it was during the Democratic Sexenio when it was really born with the founding of the Spanish Regional Federation of the First International (FRE-AIT) at the Workers' Congress of Barcelona in 1870. During the Restoration, the two major Spanish trade union organizations were founded, the socialist Unión General de Trabajadores and the anarcho-syndicalist Confederación Nacional del Trabajo, with the latter predominating until the Second Spanish Republic. CNT and UGT were the protagonists of the social revolution that took place in the Republican zone during the first months of the Spanish Civil War. During Franco's dictatorship, the two historical centers were harshly repressed until they practically disappeared. In the final stage of Franco's regime, a new organization called Workers' Commissions emerged, which together with the reconstituted UGT, will be the two majority unions from the beginning of the new democratic period until the present day.

The Unión General de Trabajadores is a major Spanish trade union, historically affiliated with the Spanish Socialist Workers' Party (PSOE).