This thesis presents an analysis of Piaroa shamanic practices that combines elements of symbolic, psychobiological and phenomenological approaches. Theories from, and clinical findings in, neuroscience, pharmacology, psychology and psychoneuroimmunology are integrated with extended participant observation field study involving basic shamanic training to demonstrate how Piaroa shamans learn to understand and effect biopsychosocial adaptation and promote health. It is argued that Piaroa shamanism is a sophisticated means of interpreting ecological forces and emotional processes in the interests of minimising stress across related systems: self, society, ecosystem, and cosmos. Piaroa shamans should be cadres in the promotion of an ethos, the good life of tranquillity, which serves as the basis for low-stress social relations. Piaroa mythology is predicated upon human-animal-god reciprocity and provides the shaman with a series of informationprocessing templates, designed to be invoked with the use of hallucinogens, which assist him to understand inter-systemic relations. I analyse how Piaroa shamans develop the psychic skills to divine and regulate ecological relationships and emotional processes, while highlighting possible relationships among native symbolism, neurology, consciousness and the emotions. It is argued that Piaroa shamanic practices involve conditioning the mind to achieve optimal perceptive capacities that, in association with sensitive biopsychosocial study, facilitate accurate prediction and successful psychosocial prescription. A cultural neurophenomenological approach enables articulation of the psychocultural logic of ethos, epistemology, divination, sorcery, and curing, and a fuller picture of a South American indigenous society’s shamanic practices than less integrative approaches have afforded