This volume contains the authentic score of the Requiem, supplemented by crucial fragments from Suessamayr's 1792 Requiem completion, plus a critical introduction to the work which attempts to untangle its genesis and structure. Christoph Wolff surveys Suessamayr's contribution, and provides a musical analysis of Mozart's composition, including contextual, structural and interpretative aspects. This is followed by an annotated collection of the principal literary documents (1791-1839) that illuminate the puzzling early history of the work.