The Socialist Unity Party of Germany was the founding and ruling party of the German Democratic Republic (GDR) from the country's establishment in 1949 until the Peaceful Revolution of 1989. Formed in 1946 through a forced merger of the East German branches of the Communist Party of Germany and the Social Democratic Party of Germany, the SED built and ruled East Germany as a one-party Marxist–Leninist state.
The SED was structured according to democratic centralism, with authority flowing from the Party Congress through the Central Committee to the Politburo. Though the Party Congress formally held supreme authority, the Politburo and the Secretariat carried out decision-making between congresses.