Nanotechnology has been described as a transformative technology, an enabling technology and the next technological revolution. Even accounting for a certain level of hype, a heady combination of investment, rapid scientific progress and exponentially increasing commercialization, point towards nanotechnology having a fundamental impact on society over the coming decades. However, enthusiasm over the rate of progress is increasingly being tempered by concerns over possible downsides of the technology. Real and perceived adverse consequences in areas such as asbestos, nuclear power and genetically modified organisms have engendered skepticism over the ability of scientists, industry and governments to ensure the safety of new technologies. As nanotechnology moves towards widespread commercialization, not only is the debate over preventing adverse consequences occurring at an unusually early stage in the development cycle; it is also expanding beyond traditional science-based risk management to incorporate public perception, trust and acceptance. Having appropriate oversight frameworks in place will be essential to the sustained development of nanotechnologies. These will need to address potentially new risks presented by engineered nanomaterials, and be responsive to the rapidity with which nanotechnologies are being discovered, developed and used. Existing oversight frameworks may be sufficiently robust to address new technologies with little modification, although some commentators suggest that this is unlikely. Either way, too little oversight could be as damaging to fledgling nanotechnologies as too much oversight.