Serenade No. 9 (Mozart)

The Serenade for Orchestra No. 9 in D major K. 320, Posthorn, was written by Wolfgang Amadeus Mozart in Salzburg, in 1779. The manuscript is dated 3 August 1779 and was intended for the University of Salzburg's "Finalmusik" ceremony that year.

The serenade is scored for 2 flutes, piccolo, 2 oboes, 2 bassoons, 2 horns, 2 trumpets, post horn, timpani and strings. It has seven movements:

1. Adagio maestoso – Allegro con spirito
2. Minuetto
3. Concertante: Andante grazioso in G major
4. Rondeau: Allegro ma non troppo in G major
5. Andantino in D minor
6. Minuetto – Trio 1 and 2
7. Finale: Presto

The Concertante and Rondeau movements feature prominent concertante sections for flutes, oboes, and bassoons.

The first trio of the second minuet features a solo piccolo played over strings. The second trio of the second minuet features a solo for the post horn. This solo gives the serenade its nickname.

A typical performance lasts approximately 45 minutes.