The leap in artistic growth between Mozart's piano concertos of 1782 (K. 413-415) and the series composed in 1784 (K. 449-451, 453, 456, 459) is one of the greatest in the composer's brief career. The Piano Concerto No. 14 in E flat major, K. 449, is generally regarded as Mozart's first mature work in the genre.

By 1784, Mozart was the star keyboard performer in Vienna. Mozart dated his manuscript of the E flat major concerto February 9, 1784. The concerto was composed for Mozart's student Barbara Ployer, whose father was an agent in Vienna for the Salzburg court. In April, Mozart would prepare another concerto for her, that in G major, K. 453.

The concerto, K. 449, is scored for piano, strings, and paired oboes and horns, although it may be played with only string accompaniment. Ms. Ployer must have been an excellent student, for the keyboard part is not easy. The structure of the work, too, is advanced and a great diversity of melodic material in the first movement requires a much larger form than in the earlier concertos. Possibly in reference to the finale and the opening of the first movement, Mozart described K. 449 to his father as "a concerto of a peculiar kind."

One great difference between K. 449 and Mozart's earlier concertos is that the first ritornello of the opening movement modulates to the dominant, an event usually reserved for the solo exposition. The opening themes and orchestration of the movement bring to mind the dramatic writing in the composer's operas with their sudden changes in mood and affective use of the minor mode. Throughout the Allegro the soloist seems more an integral part of the proceedings than the star supported by an orchestral backup. Nevertheless, the importance of the piano part is indisputable in this brief, tightly argued movement. Mozart realized one cadenza for use by Ms. Ployer.

Elegance and delicacy characterize the Andantino second movement. A perfect foil to the dramatic power of the Allegro, the Andantino's only tension stems from being set in the dominant, B flat major. Its main material consists of two successive passages, first played by the orchestra and then decorated by the soloist. The result is a movement with a through-composed feel whose wide, pathetic descending leaps look forward to the slow movements of Schumann.

The Allegro ma non troppo finale is a highly idiosyncratic structure that is like a sonata-rondo, but the contrasting material is based on variations of the first theme, creating a monothematic movement. Its overall texture is the result of Mozart's combination of contrapuntal ingenuity with opera buffa style melodies and accompaniment. The leaping, jagged principal theme makes each of its appearances in a different guise, occasionally spreading its material between different instruments. The eighth note triplets in the middle of the movement make the 6/8-meter coda less obtrusive than it might be in this seamlessly composed essay.