The musical and spiritual life of Mary Lou Williams (1910 - 1981) came together in her later years in the writing of Mary Lou's Mass. Being both Roman Catholic and a jazz pianist and composer, it was inevitable that Williams would be the first jazz composer to write a setting of the mass. The degree of success resulting from the combination of jazz and the traditional forms of Western art music has always been controversial. Because of Williams's personal faith and aesthetics of music, however, she had little choice but to attempt the union of jazz and liturgical worship. After a biography of Williams, discussed in the context of her musical aesthetics, this thesis investigates the elements of conventional mass settings and oral tradition found in Mary Lou's Mass.

This study examines the thirteenth century Artesian trouvère Adam de la Halle in the manuscript Paris, Bibliothèque Nationale f.fr 25566 as it pertains to the oral/literate model for explaining characteristics of musical traditions. The fortuitous collaboration of a single scribe with a single composer on a musical collection encompassing a cross-section of thirteenth-century styles and idioms make this repertoire uniquely appropriate to a comparison of musical oracy and literacy.

Though cadences have long been recognized as an aspect of modality, Gallus Dressler's treatise Praecepta musicae poeticae (1563) offers a new understanding of their relationship to mode and structure. Dressler's comments suggest that the cadences in the exordium and at articulations of the text are "principal" to the mode, shaping the tonal structure of the work. First, it is necessary to determine which cadences indicate which modes. A survey of sixteenth-century theorists uncovered a striking difference between Pietro Aron and his followers and many lesser-known theorists, including Dressier. The latter held that the repercussae of each mode were "principal cadences," contrary to Aron's expansive lists. Dressler's syntactical theory of cadence usage was tested by examining seventeen motets by Dressler and seventy-two motets by various early sixteenth-century composers. In approximately three-fourths of the motets in each group, cadences appeared on only two different pitches (with only infrequent exceptions) in their exordia and at text articulations. These pairs are the principal cadences of Dressler's list, and identify the mode of the motets. Observations and conclusions are offered regarding the ambiguities of individual modes, and the cadence-tone usage of individual composers.