The Dagestan Autonomous Soviet Socialist Republic (Russian: Дагестанская Автономная Советская Социалистическая Республика; 1921–1991), abbreviated as Dagestan ASSR (Russian: Дагестанская АССР; Avar: Дагъистаналъул АССР; Kumyk: Дагъыстан АССР; Lezgian: Дагъустандин АССР; Lak: Дагъусттаннал АССР; Azerbaijani: Дағыстан МССР; Aghul: Дагъустан АССР; Chechen: ДегӀастанан АССР; Nogai: Дагыстан АССР) or DASSR (Russian: ДАССР) and also unofficially known as Soviet Dagestan or just simply Dagestan, was an autonomous Soviet socialist republic (ASSR) in the Russian SFSR of the Soviet Union. This "Land of Mountains" was known also for having a "mountain of peoples," with more than thirty ethnic groups indigenous to the territory. Although as part of its strategy to promote local languages and to discourage pan-Turkic and pan-Islamic movements, a half-dozen of these ethnicities were provided with schooling in their native language at some point in Soviet history, Russian language became the most widespread second language and gradually the lingua franca, especially in urban areas.

The minor planet 2297 Daghestan, discovered in 1978 by Soviet astronomer Nikolai Chernykh, is named after the Dagestan ASSR.