The monograph analyzes the nature and evolution of organizational ties between the Third (Communist) International and its national sections in Latin America, the activities of the central and regional structures of the Comintern in the decisive decade for the formation of communist parties - 1919–1929. Particular attention is paid to the activities of emissaries of the Comintern, Profintern and CIM in various countries of Latin America and their role in the creation and evolution of left parties. The relationship between the activities of Soviet diplomats and individual communist parties has been studied in detail. The monograph is the result of many years of work by the authors in Russian and foreign archives.