Ayahuasca, a hallucinogenic plant brew from the Amazon basin used as part of healing ceremonies by the local indigenous people of the region for centuries, is now being consumed by growing numbers ofpeople throughout the world. Anecdotal evidence and previous research suggest that there are spiritual e ects experienced among participants who take part in ayahuasca ceremonies. The current study examined whether novice participants' spirituality was a ected through participation in an ayahuasca ceremony, and if so, how. A mixed-design method was used, comparing those participating in an ayahuasca ceremony to those who did not participate. This investigation used the Peak Experience Profile, the Spiritual Well-being Scale, and the Mysticism Scale as quantitative measures. Participant interviews and written accounts ofceremony experiences were analyzed. Results showed that neither the SWB score nor the M-Scale score increased significantly after participating in an ayahuasca ceremony. However, it was found that the higher the PEP score, the greater the positive change in SWB and M­ Scale scores. Qualitative data revealed common spiritual themes in many of the participants' interviews and written accounts. Experiential di erences were displayed within the ayahuasca ceremony group, warranting continued investigation into, and identi cation of, various confounding variables that prompt reported changes in spirituality within some participants while not in others. Keywords- ayahuasca, entheogen, mysticism, spirituality