The Institute of Medicine held a Forum on Smallpox; The Scientific Basis for Vaccination Policy Options on Saturday, June 15, 2002, in Washington, DC. This one-day meeting was a discussion of the scientific evidence that provides the foundation for smallpox immunization policy options. The goal of the forum was to obtain input from scientists, policymakers, clinicians, emergency responders, the public, and others on the options being considered by the federal government for smallpox immunization.