The Yiguandao (Way of Pervading Unity) was one of the major redemptive societies of Republican China. It is nowadays one of the largest and most influential religious movements of the Chinese world and at the same time one of the least known and understood. From its powerful base in Taiwan, it develops worldwide, including in Mainland China, where it nevertheless remains officially forbidden. Based on extensive ethnographic work carried out over nearly a decade, Reclaiming the Wilderness explores the expansionary dynamics of this group and its regional circulations such as they can be primarily observed from a Hong Kong perspective. It analyzes the proselytizing impetus of the adepts, the transmission of charisma and forms of leadership, the specific role of Confucianism that makes it possible for the group to defuse tension with Chinese authorities and, even sometimes, to cooperate with them. It also delves into Yiguandao’s well-structured expansionary strategies and in its quasi-diplomatic efforts to navigate the troubled waters of cross-strait politics. To readers primarily interested in Chinese studies, this work offers new perspectives on state–religion relationships in China, the Taiwan issue seen through the lenses of religion, or one of the modern and contemporary fates of Confucianism—that is, its appropriation by redemptive societies and religious organizations. But it also addresses theoretical questions that are relevant to completely different contexts and thus contributes to the fields of sociology, anthropology, and psychology of religion.