An Autonomous Soviet Socialist Republic (ASSR, Russian: автономная советская социалистическая республика, АССР) was a type of administrative unit in the Soviet Union (USSR), created for certain ethnic groups to be the titular nations of. The ASSRs had a status lower than the constituent union republics of the USSR, but higher than the autonomous oblasts and the autonomous okrugs.
In the Russian SFSR, for example, Chairmen of the Government of the ASSRs were officially members of the Government of the RSFSR. Unlike the union republics, the autonomous republics only had the right to disaffiliate themselves from the Union when the union republic containing them did so, as well as to choose to stay with the Union separately from them. The level of political, administrative and cultural autonomy they enjoyed varied with time—it was most substantial in the 1920s (Korenizatsiya), the 1950s after the death of Joseph Stalin, and in the Brezhnev Era.
According to the constitution of the USSR, in case of a union republic voting on leaving the Soviet Union, autonomous republics, autonomous oblasts and autonomous okrugs had the right, by means of a referendum, to independently resolve whether they will stay in the USSR or leave with the seceding union republic, as well as to raise the issue of their state-legal status.
The 1978 Constitution of the RSFSR recognized sixteen autonomous republics within the RSFSR. Their status as of October 2007 within the Russian Federation is given in parentheses:
Gorno-Altai Autonomous Oblast (now Altai Republic), Adyghe Autonomous Oblast (now Republic of Adygea), Karachay–Cherkess Autonomous Oblast (now Karachay–Cherkess Republic) and Khakassian Autonomous Oblast (now Republic of Khakassia) were all promoted in status to that of an ASSR in 1991, in the last year of the Soviet Union. Only the Jewish Autonomous Oblast retained its autonomous oblast status in Russia.
Other autonomous republics also existed within RSFSR at earlier points of the Soviet history: