The Declaration of 46 was a secret letter sent by a group of 46 leading Soviet communists to the Politburo of the Central Committee of the Communist Party of the Soviet Union on 15 October 1923. The declaration followed Leon Trotsky's letter, which was sent to the Politburo on 8 October and expressed similar concerns and thus laying the foundation for the Left Opposition within the Communist Party of the Soviet Union later that year. The signatories had pointed to issues with the party ban and also called for a review of the factional ban introduced in the Tenth Congress through a party conference. The vast majority of the signatories were executed during the Great Purge.

The Central Committee of the Communist Party of the Soviet Union was the highest organ of the Communist Party of the Soviet Union between two congresses. According to party statutes, the committee directed all party and governmental activities. The Party Congress elected its members.