The National Constituent Assembly (French: Assemblée nationale constituante) was a constituent assembly in the Kingdom of France formed from the National Assembly on 9 July 1789 during the first stages of the French Revolution. It dissolved on 30 September 1791 and was succeeded by the Legislative Assembly.

The Estates General of 1789, (Etats Généraux) made up of representatives of the three estates, which had not been convened since 1614, met on 5 May 1789. The Estates-General reached a deadlock in its deliberations by 6 May. The representatives of the Third Estate attempted to make the whole body more effective and so met separately from 11 May as the Communes. On 12 June, the Communes invited the other Estates to join them: some members of the First Estate did so the following day. On 17 June 1789, the Communes approved the motion made by Sieyès that declared themselves the National Assembly by a vote of 490 to 90. The Third Estate now believed themselves to be a legitimate authority equal to that of the King. Elements of the First Estate, primarily parish priests who were closer in wealth to the Third Estate compared to the bishops who were closer in wealth to the Second Estate, joined the assembly from 13 June onwards and, on 19 June, the whole of the clergy voted to join the National Assembly. A legislative and a political agenda unfolded.

There were soon attempts by King Louis XVI and the Second Estate to prevent the delegates from meeting, as well as misunderstandings on both sides about each other's intentions. Locked out of its chamber, the new assembly, led by its president Jean-Sylvain Bailly, was forced to relocate to a nearby tennis court, on 20 June; there, it swore the Tennis Court Oath, (Le serment du Jeu de Paume) promising "not to separate, and to reassemble wherever circumstances require, until the constitution of the kingdom is established and consolidated upon solid foundations." Failing to disperse the delegates, Louis started to recognize their validity on 27 June.

The Assembly renamed itself the National Constituent Assembly on 9 July and began to function as a governing body and a constitution-drafter. However, it is common to refer to the body even after then as the "National Assembly" or the "Constituent Assembly".

Following the storming of the Bastille on 14 July, the National Constituent Assembly became the effective government of France. In the words of historian François Mignet:

The assembly had acquired the entire power; the corporations depended on it; the national guards obeyed it... the royal power, though existing of right, was in a measure suspended, since it was not obeyed, and the assembly had to supply its action by its own.

The number of the Estates-General increased significantly during the election period, but many deputies took their time arriving, some of them reaching Paris as late as 1791. According to Timothy Tackett, there were a total of 1,177 deputies in the Assembly by mid-July 1789. Among them, 278 belonged to the nobility, 295 to the clergy, and 604 were representatives of the Third Estate. For the entire duration of the Assembly, a total of 1,315 deputies were certified: 330 clerics, 322 nobles, and 663 deputies of the Third Estate. Tackett noted that the majority of the Second Estate had a military background, and the Third Estate was dominated by men of legal professions.^{[page needed]}

Some of the leading figures of the Assembly at this time were: