The creation of a Bastide was a complex affair and required detailed planning. If the founding authority ( a lay or religious lord) did not own the land, he had to enter into a preliminary contract with the landowner. Before building could start, the contract had to define the amount of land made available, as well as the payment schedule. As soon as the various parties reached agreement, building could start. It is important to mention that Bastides were not always founded on empty ground, but sometimes used small existing groups of dwellings. 
Surveyors then pegged out the total area and also made a ground plan of the building plots, (known as ayrals), one per family, around the public square and the plots (known as arpents, about an acre in size), for cultivation on the edge of the village.
All that remained was to attract the peasants who would add value to the village by cultivating the ground. The privileges they were accorded represented a true revolution for that time. Above all, they became free men and were given a patch of land to do with as they pleased. The Charter of Customs or of Franchise was an important document in those troubled times, as it guaranteed in writing the persistance of these rights and also of civic duties and a code of justice. It also included prominently the laws governing the markets, which were a main preoccupation of the founding authorities. The way the markets developed in terms of their frequency and the volume of trade is an important indicator of the prosperity of a Bastide. And so the laws laid down that commercial transaction could take place only in the central square, which over time usually gained a covered hall to house the standard measuring equipment (for volumes, weights and distances) and a Town Hall, where the representative of authority lived. At the beginning this was the lord's bailiff, but was later the consul or jurat, who was designated by the inhabitants and who ensured that the terms of the contract, the charter and the code of justice were respected. 
The success of a Bastide was never guaranteed and it sometimes happened that the founding lord did not receive the expected revenues, even when the foundation had been carried out carefully and prudently. The land was then handed back to its owner. On the other hand, a successful Bastide (and success varied from one to the other) would ensure the existence of a stable urban development that would continue for centuries to come