Book excerpt: The concept of deviance has been central to the academic study of (Western) esotericism since its inception. This book, being the proceedings of the 6th Biennial Conference of the European Society for the Study of Western Esotericism (ESSWE), explores the relationship between esotericism and various forms of deviance (as concept, category, and practice) from antiquity until late modernity. The volume is the first to combine incisive conceptual explorations of the concept of deviance and how it informs and challenges the study of esotericism alongside a wide range of empirically grounded case discussions.