The origins of the Civil War of March-April 1948 and the subsequent repression of the Communists and the more militant sections of the labor movement in Costa Rica can be traced to the 1930s. The Depression accelerated the process of the formation of labor unions, notably those of the shoemakers, who were by then working in relatively large workshops of 200-300 workers, and the banana workers, who constituted a genuine agricultural proletariat. At the same time, it intensified class consciousness among labor leaders and strengthened the role played by organized labor in Costa Rican politics. The decade of the 1930s witnessed the development of the Partido Comunista de Costa Rica (PCCR), which came to dominate the Confederacion de Trabajadores Costarricenses (CTCR). It also saw the emergence of a middle-class business sector that had significant and growing conflicts with the economically and politically dominant agro-export coffee oligarchy, but which sought to promote a social and political program that was different and opposed to that of the Communist Party.

While the conservatives were trying to manage the new labor relations along the paternalistic lines that had existed between plantation owner and peon, the Communist Party and the CTCR attempted to introduce a legal framework, institutionalized in social security legislation and a labor code, to formalize workers' rights and, most importantly, collective bargaining, independent union organization, and the right to strike.