Introduction. Environmental Outdoor Education (EOE) is widely recognised as a key driver of sustainable development, fostering individuals' connection to nature, environmental empathy, and social-psychological well-being. While often focused on early childhood, EOE is equally critical during adolescence, a phase in which it can strengthen personal well-being, community engagement, environmental protection, identity, and social skills.
Purpose. This study examined the positive impact of EOE - delivered during regular school hours in secondary schools - on students' individual, social, and ecological engagement and well-being.
Methods. A longitudinal cluster randomised trial was conducted with two conditions (Intervention, n = 113; Non-Intervention, n = 89) across six waves. Intervention and Non-Intervention activities were delivered three times (Activity 1 between T1-T2; Activity 2 between T3-T4; Activity 3between T5-T6). Cross-lagged panel models (CLPM) were applied to test relationships among social skills, pro-environmental behaviour (PEB) and intentions, civic engagement, social identity, and vitality across time points.
Results. CLPM analyses revealed pathways linking EOE participation to sustainable behaviour. Gains in social skills at earlier waves predicted pro-environmental intentions at later waves, which subsequently fostered PEB. A secondary pathway - civic engagement enhancing social identity and, in turn, vitality - was promising but less consistent, with effects emerging more gradually. The first intervention cycle produced the strongest direct effects, while later cycles primarily supported the consolidation and stabilisation of these processes.
Conclusions. These findings deepen understanding of how EOE supports adolescents' development through direct engagement with natural environments. Practically, the results provide evidence for integrating EOE into school curricula as a complementary approach to classroom-based education. By demonstrating measurable benefits across social-psychological domains, this study offers a foundation for evidence-informed decisions by educators, school leaders, and policy-makers. Expanding EOE programmes may therefore serve as a strategic tool to enhance educational quality and advance sustainability goals within formal education systems.