Published in 1784, Mozart#s Sonata in A major #for clavier solo#, with the famous Rondo #Alla Turca# finale, is one of the most popular works in the entire piano literature. Now a newly resurfaced section of the autograph has prompted Bärenreiter to issue an up-to-date Urtext edition of this celebrated piece. The editor, Mario Aschauer, has set new editorial standards and offers the most innovative methodological approach of our time. His scholarly-critical performance edition is the only one to remain entirely true to the sources by presenting the musical text of the autograph and the original print separately. Both forms of the sonata are historically legitimate; the editor has not merged the sources to produce a new text. The section on performance practice provides valuable information on Mozart#s claviers as well as on the refinement of touch, articulation, pedalling and ornamentation.