Jacobin, a name applied to a political club and party during the French Revolution. During 1793–94, the most radical period of the French Revolution, the Jacobins were the ruling group. The Jacobin Club was originally known as the Society of Friends of the Constitution. It was founded in 1789 by representatives of the States-General from Brittany. The dining hall of a Dominican monastery in Paris was rented for headquarters. The Dominicans were called Jacobins in France (since their original house in Paris was on the rue St. Jacques), and the name was applied to the club. At first the Jacobins were mostly moderates who believed in constitutional monarchy. In 1791 the club grew more radical, as moderates dropped out and the general public was admitted to meetings.

By 1793 the Jacobins were the best-organized group in France. Thousands of provincial clubs were affiliated with the Paris group. Jacobin deputies voted for the death of Louis XVI. Georges Danton and Maximilien Robespierre, Jacobin leaders, used the Paris mob to intimidate the National Convention. Unlike the Girondists, a rival group in the National Convention, the Jacobins wanted a strong centralized state, governed from Paris by a small committee. In June, 1793, the Jacobins expelled the Girondists from the National Convention. The Committee of Public Safety, dominated first by Danton and later by Robespierre, instituted the Reign of Terror. Thousands were sent to the guillotine.

The Terror ended after Robespierre himself was guillotined, July 28, 1794. The Jacobin Club was closed in November.