The Armenian Soviet Socialist Republic ( Haykakan Sovetakan Soc'ialistakan Hanrapetut'yun; Armyanskaya Sovetskaya Sotsialističeskaya Respublika), also known as the Armenian SSR or Soviet Armenia, was one of the twelve original republics that made up the Soviet Union in December 1922. It was established in December 1920, when the Soviets took over control of the short-lived First Republic of Armenia and lasted until 1991. It is sometimes called the Second Republic of Armenia, following the First Republic of Armenia's demise.
As part of the Soviet Union, the Armenian SSR transformed from a largely agricultural hinterland to an important industrial production center, while its population almost quadrupled from around 880,000 in 1926 to 3.3 million in 1989 due to natural growth and large-scale influx of Armenian Genocide survivors and their descendants. On August 23, 1990, it was renamed the Republic of Armenia, but remained in the Soviet Union until its official proclamation of independence on 21 September 1991. After the dissolution of the Soviet Union, the state of the post-Union Republic of Armenia existed until the adoption of the new constitution in 1995.