 The current protocol is a pilot study of the effects and possible utility of psilocybin-facilitated experiences for professional religious leaders. We hypothesize that religious professionals, given their interests, training, and life experience, will be able to make nuanced discriminations of their psilocybin experiences, thus contributing to the scientific understanding of mystical-type experience. As we better characterize the phenomenology of psilocybin-induced mystical experiences, we may apply this knowledge to improve potential treatment studies in the future. A primary objective is to investigate changes in psychological functioning, spirituality, health, well-being, prosocial attitudes and behavior in professional religious leaders that may occur after receiving psilocybin under supportive conditions. A secondary objective is to determine whether participants who report having had the strongest mystical-type effects during psilocybin sessions will show the largest positive changes in the Interim Questionnaire. 