Since their publication in the New Mozart Edition, Mozart's sonatas K. 10–15 count as piano trios. Furthermore, the title of the first edition, published by father and son Mozart in 1765 reads "Six Sonates pour le Clavecin qui puevent se jouer avec l'accompagnement de Violon ou Flaute Traversiere”. In other words, these pieces are harpsichord sonatas that may be accompanied at will by a violin or a transverse flute. In a partial press run of the first edition a cello part was included. Our new edition is the first to take these conflicting formats into account by presenting two separate versions, one being the unaltered harpsichord part, the other a full score with separate instrumental parts for violin/flute and cello. The harpsichord part (CV 51.010/10) is indeed capable of standing by itself and requires no instrumental expansion. The melody instrument, in contrast, merely function as an accompaniment or contribute brief interjections, or, in the case of the cello, reinforce the left hand of the keyboard. In other words, K. 10–15 are not only Mozart's earliest piano trios, they are also his earliest keyboard sonatas to survive intact.