This article focuses upon the uneasy relationship between science and environmental education. It argues that science probably offers the strongest justification for the adoption of pro-environmental behaviours and policies, but that the relationship between science and environmentalism is strained by conflicts over fundamental values that are apparent in interpretation of the precautionary principle. An understanding of risk and scientific uncertainty is seen as an essential element of citizenship education for a sustainable society. Curriculum design needs to respond to the challenges of living in a risk society. The article argues for changes to the curriculum which lead to a scientific action competence founded in an understanding of the limits of science and an appreciation of the fact that scientists are moral agents who face ethical dilemmas in their work.