A conjunctivitis outbreak affecting more than 200 individuals occurred on a university campus in Evanston, Illinois, USA, in spring 2002. An investigation was conducted jointly by the Evanston Department of Health and the Illinois Department of Public Health. A combination of e-mail and traditional telephone-based surveys demonstrated that wearing contact lenses was a risk factor for any conjunctivitis and bilateral conjunctivitis, whereas using glasses was protective. Laboratory and epidemiological evidence suggested that the outbreak was caused by a viral pathogen that eluded characterization despite extensive culture and PCR-based laboratory testing. Enhanced laboratory surveillance could help clinicians and public-health officials to identify relevant secular changes in the spectrum of causes of conjunctivitis. During institutional outbreaks, e-mail surveys can help public-health officials to efficiently access information not easily collected by traditional case-control studies, and can provide an effective conduit for providing prevention recommendation, such as the need for improved hand and contact-lens hygiene during outbreaks.