Mozart's Dies irae has been transposed down a major second from the original. Scored originally for S.A.T.B. voices with an accompaniment of basset horns (alto clarinets), bassoons, trumpets, timpani, strings, and continuo, this new edition includes a keyboard reduction of the instrumental parts as the accompaniment. Modern clefs, a tempo indication and optional English words have also been added by the editor. An arrangement of this chorus for three-part mixed voices is also available.