How should the curriculum for older school students address the transition to sustainable futures? This article seeks to answer this question by reference to the marginalisation of education for sustainability (EfS) in England after 2010; its re-emergence around 2020, prompted largely by students' protests over climate change: and the continuing need for critical approaches that acknowledge the contested nature of sustainability. Gramsci's theory of hegemony as developed by Gilbert and Williams, is used to explain the marginalisation of EfS while Mouffe's advocacy of a green democratic revolution, shaped by a blend of eco-socialist, post-developmental and decolonial thought, suggests what a critical EfS should cover and why it should be linked to radical global citizenship education. Neoliberal, socially democratic and eco-socialist discourses of sustainability and a green transition should feature in the curriculum and agonistic pedagogy should be employed to enable students to reflect and act on these and so develop their political literacy. The Curriculum for Wales can accommodate such pedagogy and an incoming Labour government in Westminster can learn from its example.