This book demonstrates that the application of nanotechnology in industry can result in increased eco-efficiency and other environmental gains. It also shows what needs to be done from the side of scientists, engineers and science policy makers to guide future development in nanotechnology towards sustainability. The underlying method has been a three-tier approach of prospective technology assessment.The positive effects of nanotechnology are illustrated with four case studies. One additional case study deals with possible risks and negative effects of nanotechnology. In the last section, the role of guiding principles in future nanotechnology research and development is discussed.