A scholarly-critical edition of Puccini's only mass, based on the Urtext of the "Edizione Nazionale delle Opere di Giacomo Puccini". An examination of the autograph score has led to numerous corrections being made in the "Edizione Nazionale" compared with the old-established music text of this work. As well as this, Puccini's orchestral amendments in the Benedictus and his new arrangement of the tenor aria "Gratias agimus" from the Gloria, both dating from 1893, have been taken into consideration.