The first of its kind, this intriguing two-volume set objectively reports on and assesses this modern psycho-social movement in world culture: the constructive medical use of entheogens and related mind-altering substances. Covering the use of substances such as ayahuasca, cannabis, LSD, peyote, and psilocybin, the work seeks to illuminate the topic in a scholarly and scientific fashion so as to lift the typical division between those who are supporters of research and exploration of entheogens and those who are strongly opposed to any such experimentation altogether. The volumes address the history and use of mind-altering drugs in medical research and religious practice in the endeavor to expand and heighten spirituality and the sense of the divine, providing unbiased coverage of the relevant arguments and controversies regarding the subject matter. Chapters include examinations of how psychoactive agents are used to achieve altered states in Judaism, Christianity, Islam, and Buddhism as well as in the rituals of shamanism and other less widely known faiths. This highly readable work will appeal to everyone from high school students to seasoned professors, in both the secular world and in devoted church groups and religious colleges.