This chapter explores the ontological tensions that emerge when Indigenous epistemologies, particularly those of the Mapuche people, intersect with Western institutional frameworks in education and health. Analyzing the experiences of Mapuche children undergoing the process of becoming Machi highlights the challenges that arise when non-Western spiritual and epistemological traditions are confronted with Western educational and psychiatric paradigms. The study reveals how Western institutions often pathologize Indigenous experiences, perpetuating epistemic violence and reinforcing colonial legacies. Intercultural policies, despite their intent, fail to establish genuine epistemic equality, treating Indigenous knowledge as a cultural tradition rather than a valid framework. Institutional protocols, such as those guiding the Machi calling process in schools, shape reality through bureaucratic structures that may distort or suppress Indigenous experiences. The case of Joaquín exemplifies how multiple ontologies—biomedical psychiatry, evangelical Christianity, and Mapuche spirituality—compete in defining Indigenous children’s experiences. The chapter calls for re-evaluating institutional assumptions and a shift toward genuine interculturality that respects ontological pluralism. It urges policymakers and educators to rethink their frameworks, ensuring Indigenous epistemologies are recognized as legitimate knowledge systems rather than accommodations within Western paradigms. Without structural change, intercultural dialogue remains asymmetrical, limiting true coexistence.