The Workers and Peasants' Bloc (in Catalan: Bloc Obrer i Camperol, in Spanish: Bloque Obrero y Campesino; BOC) was a "Right Opposition" communist group in Spain. BOC was founded in Barcelona in 1931, as the mass front of the Catalan-Balearic Communist Federation (FCCB), after the merger of the Catalan Communist Party into FCCB. FCCB, which made up the nucleus of BOC, later changed its name to Iberian Communist Federation, thus stating its intention to expand itself and BOC throughout Spain.
In November 1935, the majority of BOC merged with the Trotskyist Communist Left of Spain, to form the Workers' Party of Marxist Unification (POUM; Spanish: Partido Obrero de Unificación Marxista; Catalan: Partit Obrer d'Unificació Marxista). The minority stayed out of the merger and later joined the Unified Socialist Party of Catalonia (PSUC).