Focuses on the rivalry between Gaitanismo, the left-Liberal populist mobilization led by Jorge Eliecer Gaitan and Colombian Communists in Colombia during the 1940s. Information on Gaitanismo; Origin of the struggle; Relations between Gaitanismo and the Colombian Communist Party; Role of the working class in the Gaitanista mobilization in the 1940s; Labor history of Colombia in the 1940s; Conclusions.