This volume is an interdisciplinary assessment of the relationship between religion and the FBI. We recount the history of the FBI’s engagement with multiple religious communities and with aspects of public or “civic” religion such as morality and respectability. The book presents new research to explain roughly the history of the FBI’s interaction with religion over approximately one century, from the pre-Hoover period to the post-9/11 era. Along the way, the book explores vexed issues that go beyond the particulars of the FBI’s history—the juxtaposition of “religion” and “cult,” the ways in which race can shape the public’s perceptions of religion (and vica versa), the challenges of mediating between a religious orientation and a secular one, and the role and limits of academic scholarship as a way of addressing the differing worldviews of the FBI and some of the religious communities it encounters.