When Mozart died in 1791, he left unfinished the score of his Requiem. At the request of his widow, the work was completed by Mozart's pupil and assistant, Franz Xaver Sussmayr. Unfortunately, Sussmayr was a musician of limited technique and ability--his poor orchestration has frequently been criticized, and considerable controversy has surrounded the question of whether the movements missing from Mozart's autograph were entirely Sussmayr's work, or whether he might have based them on Mozart's sketches or oral instructions. This book is an intensive new study of the background to the Requiem and the music itself. Maunder, who after many years' research has recently completed a new edition of the Requiem that attempts to be more faithful to Mozart's original intentions, presents detailed arguments concerning the authenticity of the doubtful movements, the editorial decisions he faced in preparing the new edition, the settings by other composers that may have influenced Mozart, and the problems of performance practice. He concludes that Sussmayr probably did write the disputed movements, but may have used a now-lost Mozart sketch in composing the Agnus Dei. This fascinating new study of one of classical music's best-loved works will interest a wide range of music students and scholars, and general readers.