This volume examines the Spanish Inquisition’s response to a host of self-proclaimed holy persons and miracle-working visionaries whose spiritual exploits garnered popular acclaim in seventeenth-century Spain. In an effort to control this groundswell of religious enthusiasm, the Spanish Inquisition began prosecuting the crime of feigned sanctity, attempting to distinguish “false saints” from their officially approved counterparts. Drawing on Inquisition trial records, confessors’ manuals, treatises on the discernment of spirits, and spiritual autobiographies, the book situates the problem of religious imposture in relation to the Catholic church’s campaigns of social discipline and confessionalization in the post-Tridentine era and analyzes the ways in which conceptual controversies in early modern demonology, medicine, and natural philosophy complicated the church’s disciplinary aims.