Pharmaceutical interventions, particularly vaccination, have been the principal public health method of preventing and controlling seasonal influenza. Other less invasive non-pharmaceutical interventions include the use of face masks and hand hygiene but there is little information on the effectiveness of these simple measures. Therefore we are conducting a study on the use of face masks with and without the use of hand hygiene in comparison to no intervention in residence housing units of the University of Michigan. The interventions will be carried out during a period of influenza transmission that is defined by surveillance conducted at the University Health Service. Data will be collected on use of the interventions and the occurrence of influenza and other illnesses. In all selected residence halls, when illness meeting a case definition for influenza-like illness occurs, specimens will be collected for viral isolation.