The adoption of the European Council Recommendation on learning for the green transition and sustainable development (2022) notes the critical role of education, and demonstrates the commitment of Member States to the attainment of sustainable futures. This Recommendation established a solid political foundation for co-operation in the European Education Area and formally acknowledged the need for lifelong and transformative learning to address the planetary crisis and the well-being of citizens. Formal education plays a critical role in learning for sustainability (LfS), with policy-makers paying particular attention to curriculum requirements, teacher education and school attainment. However, learning opportunities also exist outside of formal education. These are found in: communities of practice; cultural, lingustic and scientific institutions; government and private organisations, sports clubs, youth and faith groups, as well as at heritage sites, and in national parks and natural spaces. Such non-formal education offerings present diverse opportunities to experience and connect with people and planet issues; to build sustainability literacy skills and capabilities for active citizenship; to create more hands-on engagement with the natural environment; and to explore sustainable lifestyles. These opportunities extend learning beyond classrooms to involve learners and persons of all ages and backgrounds in sustainability thinking and practice. Despite the significant role played by such offerings, few data and little evidence exist that clearly define the unique contributions or impact of the non-formal education sector on the attainment of the green transition. In the absence of longitudinal data or meta-analysis, a need exists to map existing provision and to extrapolate this potential contribution from current practice.