In post-revolutionary Russia, the Union of Soviet Socialist Republics (USSR) was established, comprising a confederation of Russia, Belorussia, Ukraine, and the Transcaucasian Federation. Also known as the Soviet Union, the new communist state was the successor to the Russian Empire and the first country in the world to be based on Marxist socialism.

The Communist Party of the Soviet Union (CPSU) was the ruling Party in the Soviet Union and, therefore, its most important political institution. The Party experienced a number of name changes during its history, from its foundation in 1898, until the dissolution of the USSR and the banning of the Party in 1991.

In the USSR, all levels of government were controlled by the Communist Party.