In Citizen Science Alan Irwin explores the difficult relationship between science, society and the environment. Drawing upon sociological studies of scientific knowledge and of the risk society', the author argues that sustainable development' will not be possible without attention to questions of citizenship and citizen knowledge. Building upon a critical discussion of the relationship between science and environmental policy-making, he considers the existence of more contextual' forms of knowledge and understanding. Current discussions of, for example, the public understanding of science tend to dismiss these public assessments as uninformed or irrational. Irwin suggests that both environmental policy and environmental understanding need to be informed by such expertise. Irwin doesn't fall into the trap of using a simple pro' or anti' stance on science, but discusses the relationship between scientific understanding and the different ways in which people make sense' of environmental concerns. In conclusion, the book considers the practical possibilities for sustainable development which emerge as a consequence. Citizen Science provides a much needed route through the fraught relationship between science, the public and the environmental threat.