The Sonata in A for Violin and Keyboard, K. 526, was written in Vienna in 1787 by Wolfgang Amadeus Mozart.
It is placed in the Köchel catalogue between the string serenade Eine kleine Nachtmusik (K. 525) and the opera Don Giovanni (K. 527).
It is also considered by several authors, including Alfred Einstein, to be part of his last series of three great violin sonatas which starts with the Regina Strinasacchi sonata in B♭ K. 454 from 1784 (his annus mirabilis, the year also of the six great piano concertos 14 – 19 and the quintet for piano and winds) and continuing with the E♭ violin sonata from December 1785.
[citation needed] The first movement is a movement in sonata form in 68 time, with more evenly divided contributions between the two instruments than in the earliest of his sonatas, an exposition divided between its two tonal groups (A and E major), and a compact but unwasteful development section.
The passage just before the recapitulation brings a sequence of enharmonic changes and, for the period, wide modulations.