This mixed-methods study examines an informal place- and community-based environmental education program implemented for rural, underserved high school students in Costa Rica's bio-culturally diverse Osa Peninsula. Using a community-as-pedagogy framework built on Paulo Freire's concept of a problem-posing education, we investigate how pedagogically-positioned social relationships mediate students' knowledge, perceptions, and leadership. We find linkages between existing community resources and endogenous environmental leadership, and suggest how making those connections strengthens students' perceptions of their social relationships and their ability to create meaning and take action. Through the program, students show an increase in knowledge about their local environment. They critically and socially engage with that new information, further developing networking skills in the context of community-informed environmental issues. After participating in the program, the students describe environmental leadership as requiring persistence, forethought, and a willingness to care for both the environment and community.