In the summer of 2003, as the first global severe acute respiratory syndrome (SARS) epidemic stuttered to a close, The Royal Society set about organizing a meeting that would take stock of the year's events and ask ‘what can we learn from SARS about emerging infections in general?’ Emerging infections are more than just a current biological fashion. The bitter ongoing experience of AIDS and the looming threat of an influenza pandemic teach us that the control of infectious disease is a problem we have not yet solved. It is a problem that needs to be addressed by a broad community. Scientists, policy makers and health care workers all need to be prepared, but prepared to do what? The purpose of the meeting was to use SARS as an example to enumerate the generic issues that must be considered when planning for the control of emerging infections.