Most accounts of the consumption of ayahuasca have focused on well-established cultural patterns found in the Amazon basin. The União do Vegetal - a syncretic cult originating in the Brazilian state of Rondônia in the early 1960s - has spread well beyond this geographical range, and today possesses local groups in many of Brazil's major cities. The organization's progressive ethos and generally moralist bent has provided a means of acquiring legitimacy in a period of strong official disapproval of the use of "drugs". This study seeks to situate the growth of the cult in terms of its social composition, ritual practice, and ideological content.