This paper analyses the way how the noble families living partly in Paris but having properties in different provinces made use of the different customs to organize the transmission of their estate in their marriage contracts. It points out the reasons why most of them chose the custom of Paris. It shows that marriage, as a ‘favourable act’, gave the families some opportunities to depart from the customary laws which ruled their estate, or to depart from some articles of the customary law they chose to rule their marriage contract. But the ability to make use of this latitude was socially unequal and did not mean that noble families were able anyway to build the norms by themselves. Besides, the preferential use of the custom of Paris covers up the evolution of the clauses of the marriage contracts, which are the consequences of the socio-political transformation of nobility.