January

• On 28 January Robespierre discussed the organisation of the National Guard in the Assembly;^[1] for three years a hot topic in French newspapers.

February

• 28 February – Day of Daggers; a confrontation between the guards and nobles.

March

• 2 March
  • Claude Chappe and his brothers first demonstrated the optical telegraph.
  • Early March provincial militias were abolished and the Département de Paris was placed above the Paris Commune (1789-1795) in all matters of general order and security.
• March – The National Constituent Assembly accepts the recommendation of its Commission of Weights and Measures that the nation should adopt the metric system.

May

• On 9 May, the Assembly discussed the right to petition.^[2]
• On Sunday 15 May the Constituent Assembly declared full and equal citizenship for all free people of color.
• On 16–18 May when the elections began, Robespierre proposed and carried the motion that no deputy who sat in the Constituent assembly could sit in the succeeding Legislative assembly.^[3]
• On 28 May, Robespierre proposed all Frenchmen should be declared active citizens and eligible to vote.^[4]
• On 30 May, Robespierre delivered a speech on the abolishment of the death penalty but without success.^[5]

June

• 14 June – The abolition of the guild system was sealed; the Le Chapelier Law 1791 passed, which prohibited any kind of workers' coalition or assembly.
• 20–21 June – During the Flight to Varennes, Louis XVI and his family attempt to escape Paris, but are instead arrested at Varennes.

July

• 11 July – The ashes of Voltaire are transferred to the Panthéon. An estimated million people attended the procession.
• Between 13 and 15 July the Assembly debated the restoration of the king and his constitutional rights.^[6]
• Saturday 17 July – The Champ de Mars massacre occurs in Paris. Jean Sylvain Bailly and Marquis de LaFayette declared a ban on gathering followed by martial law.^[7][8]
• 19 July, the King was restored in his functions.

August

• 21 August – Haitian Revolution: A slave rebellion breaks out in the French colony of Saint-Domingue.
• 27 August
  • Declaration of Pillnitz: A proclamation by Frederick William II of Prussia and the Habsburg Leopold II, Holy Roman Emperor, affirms their wish to "put the King of France in a state to strengthen the bases of monarchic government."
  • Third Anglo-Mysore War: Battle of Tellicherry: Off the south-west coast of India: a British Royal Navy patrol forces a French convoy bound for Mysore to surrender.

• 29 August-5 September – 1791 French legislative election.

September

• 3 September – The French Constitution of 1791 is accepted.
• 4 September – Louis XVI receives the title of King of the French.
• 13 September – Louis XVI accepts the final version of the completed constitution.
• 14 September – The Papal States lose Avignon to France.
• 28 September – Law on Jewish emancipation is promulgated, the first such legislation in modern Europe.
• On 29 September, the day before the dissolution of the Assembly, Robespierre opposed Jean Le Chapelier, who wanted to proclaim an end to the revolution and restrict the freedom of the clubs.

October

• 1 October – The Legislative Assembly convenes.
• 6 October – The French Penal Code of 1791 is adopted.
• On 14 October a law passed to reorganize the Garde Nationale in cantons and districts; officers and sub-officers were to be elected for only one year.
• 16–17 October – Massacres of La Glacière.
• 28 October – The Declaration of the Rights of Woman and of the Female Citizen is published.

November

• On 16 November 1791 Pétion de Villeneuve was elected mayor of Paris in a contest against Lafayette.