This project studies the contributions made by Rev. Michael A. Mathis, C.S.C., to the liturgical movement in the United States during the twentieth century. After first introducing the details of Mathis' education and early work in the field of missions, the dissertation details Mathis' contributions to the liturgical movement in three major sections. First, it treats Mathis' work with liturgical education, examining the origins and development of the graduate program in liturgy at the University of Notre Dame and considering related projects before comparing Mathis' work with similar liturgical education programs. Next, it considers Mathis' work with the Divine Office, particularly in the form of his Vigil Service publications, and compares his work with other writings promoting the Divine Office and modified breviaries produced to facilitate the use of the Divine Office from his time. Finally, it examines Mathis' contributions to the Liturgical Conference and the translation of the Collectio Rituum, as well as his work preparing American Catholics for the new rites of Holy Week in 1956 and organizing the American delegation for the First International Congress of Pastoral Liturgy in 1956.