This dissertation complements those analytical studies which discuss choral works and techniques of contemporary choral composition, by examining what twentieth-century literature was actually performed within one of the choral traditions of the United States.The a cappella choral tradition has spread widely throughout the United States. Previous studies have examined the history of the pioneering a cappella choirs and the biographies of the movement's leaders. This study also complements them in examining another aspect of the a cappella tradition.Three representative choirs were chosen: the Concordia Choir from Moorhead, Minnesota, Paul J. Christiansen, conductor; the Nordic Choir of Luther College from Decorah, Iowa, Weston Noble, conductor; and the St. Olaf Choir from Northfield, Minnesota, Kenneth Jennings, conductor. These choirs were selected because each had a long tradition of touring -- consequently exposing a broader public to the literature they performed, because each choir has been widely acknowledged for performance excellence, and because each has had remarkable continuity in leadership -having only one or two conductors during the thirty-six year span included in this study.The program archives of each choir were examined to determine the twentieth-century literature which had been performed. Three conductors, Paul J. Christiansen, Kenneth Jennings, and Weston Noble, were interviewed with regard to their ideas concerning selection and preparation of twentieth-century choral music.Though each choir was found to have some distinct patterns, there were also several elements in common among the choirs:1. Each took. seriously the relationship between music and text, and the fact that the choirs were representatives of Lutheran colleges.2. Each emphasized the highest possible level of performance in order that the expressive and aesthetic qualities of the music sung would be comprehended by both singers and audience.3. Each has given a prominent place to twentieth-century music by American composers.4. Each has given a comparatively minor role to music by Scandinavian composers.5. Each has repeated certain works several times during the thirty-six years, helping to establish them in the choral repertory.6. Each has performed an approximately constant quantity of twentieth-century music during the thirty-six years, but each has tended to program progressively more challenging works as time goes on. Appendices present listings of the choral literature included in the study, of the repertory for each choir, and of currently available recordings by the three choirs of twentieth-century choral music. / School of Music