During the period when he lived in Paris, Stamitz began to cooperate with the Bohemian born clarinet virtuoso Joseph Beer (1744–1811), which proved fruitful for both Stamitz and Beer. At least one of Stamitz's clarinet concertos (the concerto No. 6 in E-flat major) seems to have been composed jointly by the two men, as both of their names appear on the title page of the Viennese manuscript. Stamitz was the first composer to specify a left-hand pizzicato (an important virtuoso device) in a musical composition. This occurs in his Viola Concerto in D major, where the passage in question is designated by an "0" above the notes.