This paper presents the current state of knowledge within our project - funded by the German Federal Ministry of Education and Research – dealing with the effects of the production and application of nanotechnological products on sustainability. It also considers suggestions made at an experts’ workshop held in Berlin on the 16th of January 2003. This publication is rather intended to contribute to the ongoing discussion on the innovation analysis and technical assessment of nanotechnologies than to be a final project report.The various contributions deal with different aspects of prospective technology assessment in the field of nanotechnology. Topics include: guiding principles as an aid to orientation and a means of shaping technologies; the “characterization of technologies” as both a generalized approach towards technology assessment and a conceptual framework for assessing actual nanotechnology applications. We review the state of the art concerning the safety of nanotechnology and its impact on the environment and health; a contribution on the toxicology of nanoparticles is also included.