This book offers a comprehensive view of the legal, political, and ethical challenges related to the global regulation of ayahuasca, bringing together an international and interdisciplinary group of scholars. Ayahuasca is a psychoactive brew containing N,N-Dimethyltryptamine (DMT), which is a Schedule I substance under the United Nations Convention on Psychotropic Substances, and the legality of its ritual use has been interpreted differently throughout the world. The chapters in this volume reflect on the complex implications of the international expansion of ayahuasca, from health, spirituality, and human rights impacts on individuals, to legal and policy impacts on national governments. While freedom of religion is generally protected, this protection depends on the recognition of a religion’s legitimacy, and whether particular practices may be deemed a threat to public health, safety, or morality. Through a comparative analysis of different contexts in North America, South America, and Europe in which ayahuasca is consumed, the book investigates the conceptual, philosophical, and legal distinctions among the fields of shamanism, religion, and medicine. It will be particularly relevant to scholars with an interest in indigenous religion and in religion and law.