The League of Communists of Serbia (Serbian: Савез комуниста Србије, romanized: Savez komunista Srbije, abbr. SKS), known as the Communist Party of Serbia (Serbian: Комунистичка партија Србије, romanized: Komunistička partija Srbije, abbr. KPS) until 1952, was the rulingpolitical party of Serbia from 1945 to 1990. It was the Serbian branch of the League of Communists of Yugoslavia, known until 1952 as the Communist Party of Yugoslavia.
Under a new constitution ratified in 1974, greater power was devolved to the various republic-level branches. In the late 1980s, the party was taken over by a faction endorsing Slobodan Milošević to become leader of the party. Milošević appeased nationalists in Serbia by promising to reduce the level of autonomy within the autonomous provinces of Kosovo and Vojvodina. This policy increased ethnic tensions with the other republics and nationalities. During the early 1990s, the growing ethnic tensions between the republics of Yugoslavia led to the break-up of the federal party.