The motet cycles known as motetti missales are among the most intriguing repertoires of late-fifteenth-century polyphony. This series features a new critical edition of the six cycles by Loyset Compère, Gaspar van Weerbeke, and Franchinus Gaffurius included in the Milanese Libroni and of the two anonymous cycles transmitted in the Leopold Codex (Munich MS 3154). For the first time this corpus is presented with uniform editorial criteria, facilitating the comparison of mensural choices and other compositional strategies. Furthermore, the introduction of each volume thematizes the peculiar characteristics of each cycle, in terms of textual choices, use of preexisting material, and musical design, allowing for a new assessment of the motetti missales that goes beyond the homogenizing stereotypes of earlier literature and accounts for the individual contributions of the various composers. The editors’ insight in this repertoire is the result of two interdisciplinary research projects financed by the Swiss National Fund and carried out at the Schola Cantorum Basiliensis in 2014–21. Of the six motetti missales cycles in the Milanese Libroni, which were copied under the supervision of Franchinus Gaffurius (1451–1522), only the cycle Salve, mater Salvatoris was composed by Gaffurius himself. Unlike the other five motetti missales cycles in the Libroni, Salve, mater Salvatoris consists not of eight motets but only four, each with two to three internal subsections. Also distinct among the motetti missales cycles is Gaffurius’s choice of texts, which, though still on Marian themes, are not centones but adaptations of two twelfth-century sequences with interpolations from the Litany of Loreto.