This dissertation analyses transformations that took place in Chicago’s African-American churches and religious culture between 1915 and 1955. It explains shifts in the worship styles and institutional structure of established Protestant churches, the rise of newer forms of religious expression, and re-conceptions of the function of black churches. I argue that the influx of Southern migrants stimulated new urban religious practices and traditions in Chicago’s black churches, and new alliances with local and national civic organizations working for racial reform. The dissertation will demonstrate that during these four critical decades of migration, the way in which Chicago’s black churches responded to Southern migrants, and to the changing religious environment tested the level of their commitment to social change and racial reform, and their vitality as religious institutions. The dissertation will historicize the religious experiences of black Americans in Chicago during a time of phenomenal demographic and cultural change, and explain how black churches negotiated dilemmas rising from their participation in the larger urban world. In a broad sense, the dissertation will underscore the relationship between African-American churches and mass society, and highlight the agency of African-Americans in the construction of their own diverse and adaptive religious cultures.