The article involves a case study research into how four student teachers taking part in a one-year teacher education programme in a university in England translate their knowledge, experiences and beliefs about Education for Sustainable Development (ESD) into classroom practice in the context of the Geography National Curriculum and ESD policies in secondary schools. The article reveals some of the ethical and political dilemmas faced by student teachers who, as committed environmentalists, struggle to resolve the tensions between the constraints of policy, school culture, school teaching materials and their own values and enthusiasms.