In the history of economic thought, Jean-Baptiste Say distinguishes himself in being both theoretician and practitioner in enterprise. Moreover, he also taught the entrepreneurial spirit in the last years of his life. We therefore find, side-by-side, a theory of production and exchanges, and a modern theory of enterprise that places him at the avant-garde of economists that have the entrepreneur as central to their work. This article presents two of the faces of Jean-Baptiste Say: Jean-Baptiste Say “entrepreneur” and Jean-Baptiste Say “theoretician of the entrepreneur” .JEL Codes : B12, B13, L26