The Encyclopédistes (French: [ɑ̃siklɔpedist]) (also known in British English as Encyclopaedists, or in U.S. English as Encyclopedists) were members of the Société des gens de lettres, a French writers' society, who contributed to the development of the Encyclopédie from June 1751 to December 1765 under the editors Denis Diderot and Jean le Rond d'Alembert.