Most studies of the religious significance of popular music focus on music lyrics, offering little insight into the religious aspects of the music itself. Traces of the Spirit examines the religious dimensions of popular music subcultures, charting the influence and religious aspects of popular music in mainstream culture today and analyzing the religious significance of the audience's experiences, rituals, and worldviews. Sylvan contends that popular music subcultures serve the function of religious communities and represent a new and significant religious phenomenon.

Drawing on ethnographic fieldwork using interviews and participant observation, Sylvan examines such subcultures as the Deadheads, raves and their participants, metalheads, and Hip Hop culture. Based on these case studies, he offers a comprehensive theoretical framework in which to study music and popular culture. In addition, he traces the history of West African possession religion from Africa to the diaspora to its integration into American popular music in such genres as the blues, rock and roll, and contemporary musical youth subcultures.