Leopold Mozart's music is inevitably overshadowed by the work of his son Wolfgang, and in any case the father willingly sacrificed his own career to promote his son's. But Leopold's Cassation in G for Orchestra and Toys (Toy Symphony), once attributed to Joseph Haydn, remains popular, and a number of symphonies, a trumpet concerto, and other works also survive.
A contemporary report described what Leopold had composed prior to 1757: "many contrapuntal and other church items; further a great number of symphonies, some only à 4 but others with all the customary instruments; likewise more than 30 large serenades in which solos for various instruments appear. In addition he has brought forth many concertos, in particular for the transverse flute, oboe, bassoon, Waldhorn, trumpet etc.: countless trios and divertimentos for various instruments; 12 oratorios and a number of theatrical items, even pantomimes, and especially certain occasional pieces such as martial music … Turkish music, music with 'steel keyboard' and lastly a musical sleigh ride; not to speak of marches, so-called 'Nachtstücke' and many hundreds of minuets, opera dances and similar items.
Leopold Mozart was much concerned with a naturalistic feel to his compositions, his Jagdsinfonie (or Sinfonia da Caccia for four horns and strings) calls for shotguns, and his Bauernhochzeit (Peasant Wedding) includes bagpipes, hurdy-gurdy, a dulcimer, whoops and whistles (ad. lib.), and pistol shots.
His oeuvre was extensive, but it has only been until recently that scholars have begun to assess the scope or the quality of it; much is lost and it is not known how representative the surviving works are of his overall output. Cliff Eisen, who wrote a doctoral dissertation on Leopold Mozart's symphonies, finds in a Symphony in G major examples of his "sensitivity to orchestral colour" and a work that "compares favourably with those of virtually any of Mozart’s immediate contemporaries."
Some of his work was erroneously attributed to Wolfgang and some pieces attributed to Leopold were subsequently shown to be the work of Wolfgang. Much of what survives is light music but there is some more significant work including his Sacrament Litany in D (1762) and three fortepiano sonatas, all published in his lifetime.