League of Communists of Yugoslavia (Serbo-Croatian: Savez komunista Jugoslavije, Савез комуниста Југославије, SKJ/СКЈ; Slovene: Zveza komunistov Jugoslavije; Macedonian: Сојуз на комунистите на Југославија), before 1952 the Communist Party of Yugoslavia (Serbo-Croatian: Komunistička partija Jugoslavije, Комунистичка партија Југославије, Slovene: Komunistična partija Jugoslavije, Macedonian: Комунистичка партија на Југославија, Komunistička partija na Jugoslavija), was a major Communist party in Yugoslavia. The party was founded as an opposition party in the Kingdom of Serbs, Croats and Slovenes in 1919.
After initial successes in the elections, it was proscribed by the royal government and remained an illegal underground group until World War II; at times, it was harshly and violently oppressed. After the collapse of Yugoslavia in 1941, partisans led by Communists became embroiled in a War of National Liberation and defeated the Axis forces and their local satellites in a bloody civil war. After the liberation from foreign occupation in 1945, the party consolidated its power and established a single party state in the Socialist Federal Republic of Yugoslavia, that existed until 1990.
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 common policy as directed by the Soviet Union and thus was expelled from the Cominform in 1948 after Joseph Stalin accused Tito of nationalism and moving to the right. After internal purges, the party renamed itself the League of Communists and adopted politics of workers' self-management and independent communism, known as Titoism.
More information on the English, Serbo-Croatian and other language Wikipedia pages.