Public perceptions of risk are a focal point of many debates about the management of hazardous technologies.Different views about what the public knows and wants often lead to quite different beliefs about what policies should be adopted and even about how society's policy-making processes should be structured.Often these views about the public are based on speculation or anecdotal observation.In the interests of having better informed debates, the present paper reviews existing empirical evidence about public risk perceptions.In doing so, it reaches a number of interim conclusions and draws forth their implications for the respective roles of technical experts and lay people in technology management.