Ideologies of language, power, and control systematically exclude minority and Indigenous languages from educational systems, including knowledge of the natural world they convey. However, the integration of multilingualism (e.g., plurilingual repertoires) as part of the United Nations’ Sustainable Development Goals agenda for inclusive educational systems and sustainability constitutes a major contemporary challenge for researchers and educators in the Global South. This chapter discusses the specificities and challenges related to student ethnicity, language, and socio-environmental context in the integration of plurilingual repertoires in a multi-ethnic Indigenous school in the periphery of Leticia (Amazon Trapezium). Addressing these challenges in light of linguistic citizenship, education for social justice, and environmental justice constitutes a first step towards introducing Indigenous languages in the school and the broader epistemic dialogue around the protection of nature.