This chapter explains to understand why no agreement was found on the matter of imprescriptibility. The interpretation of treaties on nobility and of juridical writings, confronted with the studies on noble sociology and ideology. The chapter outlines the sixteenth century and shows that imprescriptibility of nobility progressively became a problem during the Wars of Religion because of the calling into question of the bloodline of nobility. It examines how imprescriptibility became an important matter upon which the tensions of the theories of nobility focused. The chapter analyzes how these jurists' works were used by the monarchy that had to compromise with the different social practices and with the diversity of nobility. In fact, customary nobility was not thought of as a class, but rather as an adjective used in function of the places and the events of social life. The reforms of nobility and the debates over its definition in France should be compared to those in Spain.