Unión General de Trabajadores
The collectivization effort was primarily orchestrated by the rank-and-file members of the Confederación Nacional del Trabajo (CNT; "National Confederation of Labor") and the Federación Anarquista Ibérica (FAI; "Iberian Anarchist Federation"). The socialist Unión General de Trabajadores (UGT; "General Union of Workers") also participated in the implementation of collectivization.