The League of Communists of Yugoslavia, known until 1952 as the Communist Party of Yugoslavia, was the founding and ruling party of SFR Yugoslavia. It was formed in 1919 as the main communist opposition party in the Kingdom of Serbs, Croats and Slovenes and after its initial successes in the elections, it was proscribed by the royal government and was at times harshly and violently suppressed. It remained an illegal underground group until World War II when, after the invasion of Yugoslavia in 1941, the military arm of the party, the Yugoslav Partisans, became embroiled in a bloody civil war and defeated the Axis powers and their local auxiliaries. After the liberation from foreign occupation in 1945, the party consolidated its power and established a one-party state, which existed until the 1990 breakup of Yugoslavia.

The party, which was led by Josip Broz Tito from 1937 to 1980, was the first communist party in power in the history of the Eastern Bloc that openly opposed the Soviet Union and thus was expelled from the Cominform in 1948 in what is known as the TitoStalin split. After internal purges of pro-Soviet members, the party renamed itself the League of Communists in 1952 and adopted the politics of workers' self-management and independent communism, known as Titoism.

The Tito–Stalin split or the Yugoslav–Soviet split was the culmination of a conflict between the political leaderships of Yugoslavia and the Soviet Union, under Josip Broz Tito and Joseph Stalin, respectively, in the years following World War II. Although presented by both sides as an ideological dispute, the conflict was as much the product of a geopolitical struggle in the Balkans that also involved Albania, Bulgaria, and the communist insurgency in Greece, which Tito's Yugoslavia supported and the Soviet Union secretly opposed.

In the years following World War II, Yugoslavia pursued economic, internal, and foreign policy objectives that did not align with the interests of the Soviet Union and its Eastern Bloc allies. In particular, Yugoslavia hoped to admit neighbouring Albania to the Yugoslav federation. This fostered an atmosphere of insecurity within the Albanian political leadership and exacerbated tensions with the Soviet Union, which made efforts to impede Albanian–Yugoslav integration. Yugoslav support of the communist rebels in Greece against the wishes of the Soviet Union further complicated the political situation. Stalin tried to pressure Yugoslavia and moderate its policies using Bulgaria as an intermediary. When the conflict between Yugoslavia and the Soviet Union became public in 1948, it was portrayed as an ideological dispute to avoid the impression of a power struggle within the Eastern Bloc.

The split ushered in the Informbiro period of purges within the Communist Party of Yugoslavia. It was accompanied by a significant level of disruption to the Yugoslav economy, which had previously depended on the Eastern Bloc. The conflict also prompted fears of an impending Soviet invasion and even a coup attempt by senior Soviet-aligned military leaders, a fear fueled by thousands of border incidents and incursions orchestrated by the Soviets and their allies. Deprived of aid from the Soviet Union and the Eastern Bloc, Yugoslavia subsequently turned to the United States for economic and military assistance.