A central committee is a political-executive organ designated as the highest organ of a communist party between two congresses. Per the principles of democratic centralism, a central committee is empowered to deal with any issue that falls under the party's purview. While formally retaining this role in socialist states, commonly referred to as communist states by outside observers, in practice, it delegates this authority to numerous smaller internal organs due to the infrequency of its meetings. The term of a central committee of a ruling communist party is usually five years. The party congress elects individuals to the central committee and holds it accountable. At the first central committee session held immediately after a congress, it elects the party leader, an office usually titled general secretary of the central committee, a political organ, commonly known as the politburo, and an executive organ, customarily named the secretariat.

Communist parties are organised on Leninist lines based on the principles of democratic centralism. Adolf Dobieszewski, an official of the Central Committee of the Polish United Workers' Party (PUWP), tried to define democratic centralism in 1980. He posited that centralism involves unifying party building and policy to construct a socialist society. To achieve unity in party building and policy, Dobieszewski contended that the minority had to be subordinate to the majority. Secondly, he posited that lower-level organs were subservient to higher-level organs. Third, members willingly acquiesced to discipline, and political discipline was equally obligatory for all party members. Democracy, on the other hand, meant, according to Dobieszewski, that every member had equal opportunity to participate in the formulation of the party's programme and line, as well as the right to elect and recall officials at all levels.

Power was organised as a uniform structure, with the highest party organs, such as the congress, functioning as the party's "supreme organ". This supreme organ is responsible for electing the central committee, which is typically tasked with directing the work of the communist party in between two congresses. According to scholar Baruch Hazan, the former ruling Eastern European communist parties provided nearly identical descriptions of the functions and powers of their central committees. Their responsibilities included representing the party externally, organising party organs, directing their activities, nominating personnel for internal organs, evaluating party cadres, and administering internal funds. Additionally, they were responsible for overseeing the work of state organs, granting approval to the state plan and budget ahead of the discussions in the supreme state organ of power (SSOP), and endorsing the appointments of individuals to prominent state roles. However, more generally, central committees are empowered to deal with any issue that falls under the party's purview.

Most communist states formally enshrine the communist party's leading or guiding role in state and society, and this is institutionalised by giving the party two-thirds of the seats in the supreme state organ of power (SSOP), which has complete control over all state activities per the principle of unified power. These members are, in most cases, elected in non-competitive elections and stand as candidates on the approval of the central committee.

Many central committee members also serve concurrently as members of the SSOP. In the Soviet Union, 227 out of 241 members of the Central Committee of the 24th Congress of the Communist Party of the Soviet Union (CPSU) concurrently served in the Supreme Soviet of the Soviet Union. They tended to dominate the Supreme Soviet and occupied leading political positions within it. In 1971–1973, forty per cent of debate participants were either members or alternates of the central committee. Party members who serve in the SSOP are also bound by party discipline and have to enact policies approved by the central committee.

The leading role principle entails that the central committee adopts recommendations on state policy on behalf of the party to, most commonly, the SSOP, but also to other state organs if deemed necessary. For instance, the Central Committee of the Hungarian Socialist Workers' Party (HSWP) "adopted recommendations for filling of jobs in the state apparatus" to the SSOP, the National Assembly, on 29 March 1979. In other instances, the central committee could instruct its members to resign from state offices. The 7th Session of the Central Committee of the 8th PUWP Congress, held on 1–2 December 1980, instructed Edward Babiuch, Jerzy Łukaszewicz, Tadeusz Pyka, Jan Szydlak, Tadeusz Wraszczyk, and Zdzisław Zandarowski to resign their seats in the Sejm, the SSOP in the People's Republic of Poland, and instructing its former leader, Edward Gierek, to resign from his seat in the State Council.

The central committee could also nominate individuals to state positions. On 11 April 1984, during the 1st Session of the 11th Supreme Soviet of the Soviet Union, Mikhail Gorbachev nominated Konstantin Chernenko as chairman of the Presidium of the Supreme Soviet of the Soviet Union "on instructions of the Central Committee". Upon his election, Chernenko nominated Nikolai Tikhonov as chairman of the Council of Ministers, the Soviet government, also on the instructions of the Central Committee. Moreover, Chernenko and Gorbachev both stated that the instruction had also been "approved by the party group" of the Supreme Soviet.

Marxist constitutional theorist Sylwester Zawadzki, and member of the SSOP of Poland, defined the relationship between the party and state as follows, "The Marxist-Leninist party gives political direction to the work of both the [SSOP] and the Government. [SSOP] and Government both work to carry out a common program for building socialism. It does not mean, however, that under these conditions the importance of the [SSOP's] constitutional functions is reduced."