Martin B. Hellriegel papers are comprised of articles, audio tapes, correspondence, diaries, lectures, pamphlets, publications, and sermons. The collection primarily concerns Hellriegel's contributions to the liturgical movement in the Catholic Church, which advocated for increased participation in and understanding of liturgy by lay Catholics. Hellriegel was especially active in teaching, preaching, and creating new settings for Masses and other services. The collection also includes materials produced during Hellriegel's regular activities as a parish priest and chaplain to religious sisters, and correspondence with friends, family, and colleagues.