In the Mozart Year 2006, Henle will begin publication of all of Mozart's string quintets in a three-volume Urtext edition (parts and study scores). Volume II, comprising the best-known and most often played quintets in C major (K. 515), g minor (K. 516) and c minor (K. 406/516b) from 1787 is the first to appear. This Urtext edition contains an exciting finding: it draws upon a hitherto unknown source. Recently Ernst Herttrich, one of the two editors, found handwritten parts for these works, containing additions in Mozart's hand - predominantly concerning dynamics and articulation.