Acute respiratory infections such as pneumonia and influenza are an enormous public health problem, and trends suggest that the burden of disease due to respiratory infection is likely to get worse rather than better in the coming years. This Gordon Research Conference (GRC) will focus attention on the biology of acute respiratory infections. The goal is to foster communication among individuals and groups which are studying this common and important problem from distinct vantage points, to develop and encourage creative and multidisciplinary approaches to discovery. Perspectives to be considered include microbiology, immunology, physiology, and population biology. Elucidating the biology of respiratory infections will facilitate the development of innovative, effective prevention and treatment strategies for acute respiratory infections.