This book examines the nearly one-quarter of American and Canadian adults who say they have no religion. Who are they? Why, and where, has this population grown? How do religious nones in the United States and Canada compare? What are the dynamics of being a religious none in contemporary America and Canada, and how does this willful distance from organized religion impact other aspects of daily and social life? This book turns to survey and interview data to answer these questions against the backdrop of three theoretical frameworks in the sociology of religion: stages of decline, individualization and spiritualization, and polarization. The central claim is that there is a gradual religious decline happening in stages across time and generations and at different rates in various social, cultural, and regional contexts, leading to the rise of religious nones. Yet, this form of decline does not imply the disappearance of all things religious and spiritual, as a diversity of spiritual beliefs and practices along with nonbelief and secular attitudes coexist and are constantly evolving. The decline of organized religion among large segments of the American and Canadian populations also does not mean that religion is necessarily less relevant for everyday interactions and social life. If anything, that there are now large groups of religious and nonreligious individuals coexisting in both countries could mean there is a greater social divide and distance in moral and political values and behaviors along religious/nonreligious lines, as well as in interactions and attitudes between the religious and nonreligious.