Organization of the Communist Party of the Soviet Union
The organization of the Communist Party of the Soviet Union was based on the principles of democratic centralism. The governing body of the Communist Party of the Soviet Union (CPSU) was the Party Congress, which initially met annually but whose meetings became less frequent, particularly under Joseph Stalin (dominant from the late 1920s to 1953).
Source: Wikipedia — Organization of the Communist Party of the Soviet Union (CC BY-SA 4.0)