Non-hegemonic perspectives on sustainability are grounded in environmental sustainability based on justice. We argue about the potential of co-operatives for learning framed through degrowth epistemological visions promoting pedagogical changes in Higher Education. The context is a public university in Catalonia (Spain) implementing an innovative teaching methodology merging service learning and co-operatives for learning in an Environmental Sciences degree. The research question was: What are the experiences of undergraduate students participating in co-operatives for learning about environmental education? Data collection used focus group interviews and individual reflective narratives. Based on the construct of dialectical tensions, we identify three breaking points for the transition to teaching justice-based environmental sustainability using co-operatives for learning: (1) decommodification of work (tradition/innovation; theory/practice); (2) reconstruction of relationships with 'the other' (individual/collective); and (3) with nature (capitalism/degrowth). We conclude that students' environmental praxis is promoted when addressing new perspectives of development and sustainability in university teaching.