Communist Party of the Soviet Union

The Communist Party of the Soviet Union (Russian: Коммунистическая партия Советского Союза, КПСС, Kommunisticheskaya partiya Sovetskogo Soyuza), abbreviated in English as CPSU, was the founding and ruling political party of the Union of Soviet Socialist Republics (USSR). The CPSU was the sole governing party of the Soviet Union until 1990 when the Supreme Soviet annulled the law which granted the CPSU a monopoly over the political system. The party was founded in 1912 by the Bolsheviks (the majority faction of the Russian Social Democratic Labour Party), a revolutionary group led by Vladimir Lenin which seized power in the aftermath of the October Revolution of 1917. The party was dissolved on 29 August 1991 soon after a failed coup d'état.

The CPSU was organized on the basis of democratic centralism, a principle conceived by Lenin that entails democratic and open discussion of policy issues and the requirement of unity in upholding agreed policies. The highest body within the CPSU was the party Congress, which convened every five years. When the Congress was not in session, the Central Committee was the highest body. Because the Central Committee met twice a year, most day-to-day duties and responsibilities were vested in the Politburo, the Secretariat, and the Orgburo (until 1952). The party leader was the head of government and held the office of either General Secretary, Premier or head of state, or some of the three offices concurrently—but never all three at the same time. The party leader was the de facto chairman of the CPSU Politburo and the chief executive of the USSR.