Popular music in the twenty-first century is increasingly divided into niche markets. How do fans, musicians, and music industry executives define their markets' boundaries? What happens when musicians cross those boundaries? What can Christian music teach us about commercial popular music? In God Rock, Inc., Andrew Mall considers the aesthetic, commercial, ethical, and social boundaries of Christian popular music, from the late 1960s, when it emerged, through the 2010s. Drawing on ethnographic research, historical archives, interviews with music industry executives, and critical analyses of recordings, concerts, and music festival performances, Mall explores the tensions that have shaped this evolving market and frames broader questions about commerce, ethics, resistance, and crossover in music that defines itself as outside the mainstream.