The All Russian Constituent Assembly (Russian: Всероссийское учредительное собрание, romanized: Vserossiyskoye uchreditelnoye sobraniye) was a constituent assembly convened in Russia after the February Revolution of 1917. It met for 13 hours, from 4 p.m. to 5 a.m., 18–19 January [O.S. 5–6 January] 1918, whereupon it was dissolved by the Bolshevik-led All-Russian Central Executive Committee, proclaiming the Third All-Russian Congress of Soviets the new governing body of Russia.

The 1917 Russian Constituent Assembly election did not produce a democratically elected government, as the Bolsheviks, who were in power since the October Revolution which occurred prior to the election, subsequently disbanded the Constituent Assembly and proceeded to rule the country as a one-party state with all opposition parties outlawed. Some scholars have had a differing view and attributed the establishment of the one-party system in the Soviet Union to the wartime conditions imposed on the Bolshevik government and others have highlighted the initial attempts to form a coalition government with the Left Socialist Revolutionaries.

A democratically elected Constituent Assembly to create a Russian constitution was one of the main demands of all Russian revolutionary parties prior to the Russian Revolution of 1905. In 1906, the Tsar decided to grant basic civil liberties and hold elections for a newly created legislative body, the State Duma. However, the Duma was never authorized to write a new constitution, much less abolish the monarchy. Moreover, the Duma's powers were falling into the hands of the Constitutional Democrats and not the Socialists. The government dissolved the Duma, as was their legal agreement, in July 1906 and, after a new election, in June 1907. The final election law written by the government after the second dissolution on 16 June [O.S. 3 June] 1907 favored the landed and ruling classes. The Duma was therefore widely seen as unrepresentative of the poorer peasants and working classes. Demands for a Constituent Assembly that would be elected on the basis of universal suffrage continued unabated. But what little the Duma could do after 1907 was often vetoed by the Emperor or the appointed upper house of the Russian parliament.

With the abdication of Tsar Nicholas II in the February Revolution of 1917, power in Russia passed to a Provisional Government formed by the liberal leadership of the Duma.

The Provisional Government was so named because it was made up of parliamentary figures, last elected (as the Fourth Duma) in 1912, who claimed provisional authority for managing the revolutionary situation in the midst of the First World War until a more permanent form of government could be established by an elected Constituent Assembly.

Grand Duke Michael had refused to ascend to his older brother Nicholas II's throne without the consent of an elected Constituent Assembly, and it was broadly assumed that an elected Constituent Assembly was the only body with the authority to change Russia's form of government. The Provisional Government claimed that it would organize elections once the First World War had concluded, but in spite of the initial agreement in July 1917, they declared Russia a republic and began preparations for elections in the "Preparliament", later named the Council of the Russian Republic. These actions triggered criticism from both left and right. Monarchists saw the declaration of a republican form of government in Russia as unacceptable, while the left considered the declaration a power grab intended to weaken the influence of the Soviets.

The Bolsheviks' position on the Constituent Assembly evolved during 1917. At first, like all the other socialist parties, the Bolsheviks supported the election of a Constituent Assembly. Vladimir Lenin himself later argued: 'The demand for the convocation of a Constituent Assembly was a perfectly legitimate part of the programme of revolutionary Social-Democracy, because in a bourgeois republic the Constituent Assembly represents the highest form of democracy'.

But there was a potential contradiction in Bolshevik policy. Since Lenin's return from Switzerland in April 1917, the Bolsheviks had distinguished themselves from other socialists by calling for "All Power to the Soviets". The Bolsheviks thus opposed "bourgeois" parliamentary bodies, like the Provisional Government and the Constituent Assembly, in favour of the Soviets (directly elected revolutionary councils of workers, soldiers and peasants) which had arisen after the February Revolution.