In the common listing of Mozart's symphonies, the largest chronological gap occurs between 1774 and 1778, spanning the interval from the symphony designated No. 30 to No. 31, the "Paris" Symphony. During that period, however, he wrote five serenades. Mozart's serenades of this period are no less substantial than his symphonies: at the time, in fact, the symphony was considered merely a secondary attraction as part of some event or theatrical evening, while a serenade was normally written expressly for an occasion and was intended to serve as the featured work. In Salzburg, serenades had developed into a highly developed and conventional form; thriftily, Mozart often constructed them in such a way that several movements could be extracted (and sold) as a complete symphony, while others could sometimes be assembled as a concerto. Three movements of the present work by Mozart were circulated as an independent symphony, and the "Concertante" and "Rondeau" movements were also later reconstituted as a Sinfonia concertante in G major.

The August composition date of the present work strongly suggests that it was written for the annual graduation ceremonies of the University of Salzburg. The Serenade is scored for strings, two oboes, two bassoons, two horns, two trumpets, and kettledrums; the use of a harpsichord continuo is optional.

The Serenade proper is preceded by and concluded with a march. The first movement begins with an emotional slow introduction, which without delay opens into an ebullient sonata-allegro. The Concertante features a scaled-down grouping of the flutes, oboes, and bassoons (the latter in unison); at one point the instruments all participate in a simultaneous cadenza. With the Andantino, the Serenade undergoes a remarkable change of mood; the prevailing light character darkens into melancholic, even tragic, seriousness. In the second trio of the following Minuet, Mozart calls for the posthorn—a valveless instrument once used to announce the arrival of a postal coach—that gives the work its familiar appellation. The Presto is one of the most exhilarating of Mozart's finales, flowing by in a rapid, breathless flurry of notes.

© All Music Guide