Mozart's mass was first performed in Salzburg in October 1783, with Mozart's wife, Constanze, singing the soprano solos. For this edition, Richard Maunder has completed the orchestration of the two Credo movements and reconstructed the Sanctus and 'Osanna', taking full account of Mozart's division of the voices into two choirs. The vocal score includes an orchestral reduction for rehearsal purposes, and details of original sources and editorial practice may be found in the full score.