Mozart wrote his only concerto for clarinet and orchestra for his friend Anton Stadler in the space of about ten days, when he was at the height of his powers, and only two months before his tragically early death. In Mozart's day the clarinet was still quite a new instrument, and was undergoing development by various makers. Mozart wrote for Stadler's own instrument - a "Bass-Klarinett". This was not the instrument we now know as a bass clarinet, but an extended normal clarinet, capable of playing a whole major third lower than the modern instrument. The concerto has survived not in Mozart's manuscript, but in a set of parts with the clarinet solo written for normal clarinet, issued in 1801 - ten years after Mozart's death. It was published by the firm of Johann Andre, who had bought all Mozart's surviving manuscripts from his widow, Constanza, in 1799. It is presumed, but by no means certain, that the arrangement for normal clarinet was by Andre himself. Despite its curious birth, this is a glorious work: the first great concerto for the instrument, and some would say still the greatest. The solo part displays the range and agility of the instrument as well as its velvety and soulful qualities, particularly exploring the differences between the higher and lower registers. Notice how Mozart omits the oboes and clarinets from the orchestra, in order to leave the middle woodwind register free for the soloist to exploit.

The first movement, in classical sonata form structure, is a wide-ranging and continuous melody. Although it is rich and varied in its ideas, the occasional chromatic passages and the soft phrase endings subtly impart a melancholic character.

The outer sections of the slow movement are simple but warm and rich. The middle section, like the coda, is more elaborate for the clarinet, much of it in the lower register.

The rondo, based on the interplay of two melodies, provides a mostly high-spirited conclusion, yet moments of sadness still persist. I find it amazing to think that, just nine weeks after writing this concerto, Mozart was dead.