Georgius Adamus Josephus [Joseph] Schmitt (18/03/1734 - 28/05/1791), a German-Dutch composer and publisher, born in Gernsheim am Rhein, died in Amsterdam. Joseph Schmitt has always mainly been thought of as a composer and as a music director at Felix Meritis. Here, his activities as a music publisher and music seller have been studied. Nothing remains of his business but copies of his editions. These are not dated; there is no correspondence or archive left. Research into Schmitt’s editions using contemporary information found in advertisements and publishers’ catalogues made it possible to date the editions quite precisely. After this it was possible to trace Schmitt’s business contacts. Initially, Schmitt was particularly interested in the London music business. He was one of the first Dutch publishers to establish exchanges with high-profile London music publisher John Bland. Schmitt, who clearly favoured instrumental chamber music over vocal compositions and who always provided his clientele with music editions of the highest quality, emerges as a keen entrepreneur who strived to be on top of the latest compositions from composers of standing.