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). Party Congresses would elect a Central Committee which, in turn, would elect a Politburo and a Secretariat. Under Stalin, the most powerful position in the party became the General Secretary, who was elected by the Politburo and Secretariat. In 1952 the title of General Secretary became First Secretary and the Politburo became the Presidium; the names reverted back to their former forms under Leonid Brezhnev in 1966.
In theory, supreme power in the party was invested in the Party Congress. However, in practice the power structure became reversed and, particularly after the death of Lenin in January 1924, supreme power became the domain of the General Secretary.
In the late Soviet Union the CPSU incorporated the communist parties of the 15 constituent republics (the communist branch of the Russian SFSR was established in 1990). Before 1990 the communist party organization in Russian oblasts, autonomous republics and some other major administrative units were subordinated directly to the CPSU Central Committee.
At lower levels, the organizational hierarchy was managed by Party Committees, or partkoms (партком). A partkom was headed by the elected "partkom bureau secretary" ("partkom secretary", секретарь парткома). At enterprises, institutions, kolkhozes, etc., they were called as such, i.e., "partkoms". At higher levels the Committees were abbreviated accordingly: obkoms (обком) at oblast (zone) levels (known earlier as gubkoms (губком) for guberniyas), raikoms (райком) at raion (district) levels (known earlier as ukoms (уком) for uyezds), gorkom (горком) at city levels, etc.
The same terminology ("raikom", etc.) was used in the organizational structure of Komsomol.
The bottom level of the Party was the primary party organization (первичная партийная организация) or party cell (партийная ячейка). It was created within any organizational entity of any kind where there were at least three communists. The management of a cell was called party bureau/partbureau (партийное бюро, партбюро). A partbureau was headed by the elected bureau secretary (секретарь партбюро).
At smaller party cells, secretaries were regular employees of the corresponding plant/hospital/school/etc. Sufficiently large party organizations were usually headed by an exempt secretary, who drew his salary from the Party money.
All aspects of the Party's life came under vigorous debate within leading Party circles. However, during Vladimir Lenin's lifetime, all of these debates ended with the victory of the position that he espoused. Following his death, the maneuvering between different groups of Party leaders for the succession saw conflict between a group around Stalin and, successively, Leon Trotsky, the Left Opposition, the United Opposition, and the Right Opposition. In all cases, Stalin and his supporters were victorious. With the defeat of the Right Opposition in 1929, Stalin emerged as Party leader. He consolidated his position during the 1930s, especially through the Terror of 1936 to 1938, emerging as the vozhd, or unquestioned leader of the party and the people. This process of a shift from the collective leadership of the Lenin years to the personal dictatorship of Stalin had direct implications for the Party. In the initial years of power, leading Party organs were real arenas of debate and conflict, and although Lenin manipulated Party organs, the principal basis upon which he was victorious in inner-party conflict was his ability to persuade sufficient members to support the position he advocated. With Stalin's personal dictatorship, party organs ceased to be the scene of open political debate and instead became stylized assemblies for the laudation of Stalin. While this was not as much the case at the level of the Politburo, even here the cut and thrust of debate was blunted by the personal dominance of Stalin.