What lies at the heart of environmental identity is the recognition of our interconnection with other people, living and not yet born, as well as nonhumans. To develop this sense of belonging, one needs to sustain public connection—a basic orientation to the public world where matters of shared concern are addressed. This connection is best sustained through communication— interpersonal and through media. The purpose of this dissertation is to explore the role that public connection, interpersonal and mediated, plays in young people’s everyday environmental engagement. This dissertation addresses the task by focusing on how this role varies among adolescents of different ages, genders, and existing environmental attitudes and how it changes over time. Drawing on Bruno Latour’s notion of “matters of concern” and Steven Vogel’s environmental philosophy, this inquiry challenges the common understanding of environmental awareness as an “extremely scientific view of the world,” expands the role of the media and interpersonal communication beyond the dissemination of scientific and ecological information and its effects on people, and taps into communication’s potential to sustain public connection. To provide a more integrated and dynamic perspective on adolescents’ communication flows, I employ longitudinal quantitative data and draw heavily on a toolbox of person-oriented methods. Methodologically, the main focus lies in identifying types of young people who function in a similar way and comparing how the relationship between public connection and environmental engagement unfolds for these different types of individuals. This dissertation consists of three empirical studies. The findings suggest that the more strongly connected to the public world young people are, the more engaged they are with environmental issues. Both interpersonal discussions and news media use assist in strengthening engaged adolescents’ belief that their contribution matters for tackling climate change. However, environmentally aware youth may project their own beliefs onto other people rather than being influenced by others’ beliefs. Disengaged youth do not sustain public connection, whether through conversation or through media. The role of mediated public connection varies among adolescents. Media may not be the most important channel for environmentally engaged youth to sustain their orientation to the public realm. This is indicated by the deep gender divide, in which girls are more concerned about the environment but consume significantly less news than boys. While news consumption does not seem to contribute to environmental disengagement, its relevance to pro-environmental practices weakens as teenagers mature. Early adolescence may be a critical window of opportunity to instill values of connectivity and form everyday habits that can help us achieve a more sustainable future.