Most of the sixteen masses in the Breitkopf and Härtel complete edition of Mozart’s works are supposed to have been youthful compositions, which, though suggestive of other works of the master, fall far short of his usual skill. According to Köchel, however, the masses published by Novello are not all genuine; such are those in E-flat (Novello, Nos. 13 and 16), and in C (No. 17). Jahn and Köchel both agree in believing that the one in B-flat (No. 7, Novello, but published originally by Peters) is not Mozart’s and base their contention not only on the use of the clarinets, which were not present in his Salzburg orchestra, but on the fact that Mozart’s widow credited Süssmayer with being the composer of the work. Other doubtful ones are two short masses in C and G (Novello, Nos. 8 and 9), one in G (Novello, No. 12) and a short Requiem in D minor which Köchel discards because of his certainty that Mozart never wrote but one Requiem, his last, unfinished work. The fact that Mozart’s compositions were circulated mostly in manuscript form and that few of them were published during his lifetime, may be largely responsible for the error of attributing these masses to him and composers of small attainments may have used this means for getting a hearing for their works. A Mass in C, known as the ‘Coronation Mass’ (why this name, is not known) was evidently patched together from his opera _Cosi fan tutte_, though some authorities believe that he himself compiled the opera from the mass. The incomplete Mass in C minor is known to be genuine, though he afterwards used a large part of it in his _Davidde penitente_. This mass was begun in 1782 and was intended for performance as a sort of thank-offering upon his marriage to Constance Weber and it had one performance on Aug. 25, 1783, in St. Peter’s Church, Salzburg. He did not complete it for the ceremony, however, and the missing numbers were supplied by him with material from his other works. The work is uneven in quality, some of it being very immature and almost trivial, while other parts, such as the _Kyrie_ and _Gratias_, do not fall far below the ‘Requiem.’ Aloys Schmitt endeavored to complete the work in order to make it available for church-service. As the _Agnus Dei_ was missing, he repeated the music of the _Kyrie_ and, to complete the unfinished _Credo_, he inserted unfamiliar sacred compositions of Mozart’s, thus using the composer’s own material and inserting his own harmonies, here and there, merely to connect the parts. V