AbstractJoseph Ahrens (1904–97) was a twentieth-century German composer, virtuoso organist, and teacher. He was a professor of church music at the Berlin Academy of Music (Berlin Hochschule fur Musik), organist at the Cathedral of St. Hedwig, and choir director and organist at the Salvator Church in Berlin. He contributed to twentieth-century church music, especially of the Roman Catholic Church, and composed many works for organ and various choral forces. His organ pieces comprise chorale-based pieces, free (non-chorale) works, liturgical pieces, and serial compositions. He was strongly influenced by twentieth-century German music trends such as the organ reform movement, neo-baroque style, and, in his late period, serial techniques. This document examines one freely composed work and two serial compositions by Joseph Ahrens: Canzone in cis (1944), Fantasie und Ricercare (1967), and Trilogia Dodekaphonica (1978). The purpose is to demonstrate that Ahrens’s style developed throughout his career, from a post-Wagnerian harmonic language to one that adopted twentieth-century techniques, including serialism, while retaining the use of developed thematic material and a connection to neo-baroque characteristics in terms of forms and textures.