Ferdinand de Saussure was the Adjunct Secretary of the Société linguistique de Paris between 1882 and 1891. Eleven of Saussure’s letters have been kept in the Society’s archives. The aim of this paper is to edit and present these eleven new letters by placing them in their respective contexts. This unpublished exchange brings new insights into Saussure’s work at the Société linguistique de Paris, in particular his relationship with Jean Psichari.