Instituted in 1258 by a group of barons directed by Simon V of Montfort, 6th Count de Leicester, the Provisions of Oxford are often regarded as the first English Constitution.

The Provisions forced the king Henry III of England to accept the new shape of government in which the capacity was placed between the hands of a council of 15 members having to supervise the ministerial appointments, local government and guard of the royal castles. The Parlement, which met three times per annum, was to supervise the activities of this council. One can advance that this document is of importance equal or higher than the Large Charter of 1215. For the first time, the English Crown was forced to recognize the rights and the powers of the Parliament.

A written confirmation of the agreement was sent to the sheriffs of all the counties of England. It was written in Latin, French and, which is significant, in English. The use of English was a symbol of the anglicisation English government and an antidote with the gallicisation operated in the previous decades.

The Provisions of Oxford were replaced the following year by the Provisions of Westminster.

These Provisions were abolished by Henry III in 1262, with a sanction of the Pope, which marked the beginning of the Second War of the Barons (1263-67), gained by the king.

In 1264, that was cancelled last once by the Dictum de Kenilworth.