Scholars and policymakers have increasingly advocated to engage citizens more substantially in the development of science and technology. However, to a large extent it has remained unknown how citizens can contribute to technology development. In this study, we systematically characterized citizens’ contributions in the development of nanotechnology for health. We explored to which technology aspects citizens are able to provide suggestions on and on which values their suggestions are based. Fifty citizens in the Netherlands were asked to discuss different applications (...) of nanotechnology for health. They were divided over eight focus groups, which lasted approximately 6.5h each. The citizens were able to contribute to various technology aspects; they mainly focused on the technologies’ implementation and use, they paid some attention to the development and system aspects, and also addressed, but less, the design and communication aspects. Their suggestions were often derived from concerns about the potential effects of the technologies and were predominantly based on the values of well-being, autonomy, and privacy. (shrink)