This special supplement of Nature Medicine, directed at the topic of emerging infectious diseases, is very timely. Recent high-profile outbreaks have highlighted the global risk that infectious agents, both new and old, represent for society. The experience of severe acute respiratory syndrome (SARS) shows the risk posed by emerging infectious diseases, but also the power of strongly coordinated global surveillance and public health measures, coupled with scientific research, to keep infection under control1,2. Diseases such as drug-resistant malaria continue to be threats. There is a need to enhance global resources to investigate, detect and respond to emerging infections, and to appropriately coordinate and direct research efforts to meet the challenges presented by these diseases.