In response to the impetus that is gathering in the UK for upstream public engagement, we analyze the impacts of the Royal Society and Royal Academy of Engineering report of 2004 on Nanoscience and Nanotechnologies: Opportunities and Uncertainties. The paper presents an analysis of 24 interviews with stakeholders to the nanotechnology debate. It uses these to discuss the inquiry process and the recommendations contained within the report, as well as to explore and critique the notion of “upstream.” We find broad support for the inquiry, which was positioned by many stakeholders itself as upstream, primarily because of its broad framing and wide stakeholder involvement. A number of both explicit and implicit upstream elements are also contained within its recommendations. However, the interviews also suggest that the notion of upstream engagement is a contested concept with a range of associated dilemmas and tensions. In drawing out some of the promise and perils of moving public debate upstream, the paper concludes that there is a risk of merely replacing the perceived deficit in public understanding of science with a perceived deficit in public engagement with science.