Ayahuasca is a psychoactive infusion that has been used as an entheogen for centuries, with recent research indicating its potential as a promising treatment for certain clinical disorders. Despite the growing scientific literature on its effects, there remains a scarcity of studies examining the subjective experiences of naïve ayahuasca users. The first study in this dissertation aimed to assess the subjective experiences of naïve individuals, including those with depression and healthy controls, following ayahuasca consumption. The second study evaluated the relationship between prior ayahuasca experience and health outcomes, beliefs, and cognitive factors, comparing naïve, low/moderate, and high-experience users who consumed ayahuasca in naturalistic settings.