At the World Health Assembly in May 1980, the World Health Organization declared the world free of smallpox. Smallpox vaccination of civilians is now indicated only for laboratory workers directly involved with smallpox or closely related orthopox viruses. However recent questions raised by the terrorist attacks in fall 2001 have renewed concerns about possible outbreaks of smallpox resulting from its use as a biological weapon. In June 2002, the Institute of Medicine convened a public conference to discuss the scientific, clinical, procedural, and administrative aspects of various immunization strategies. Scientific and Policy Considerations in Developing Smallpox Vaccination Options summarizes the presentations and discussions from this workshop.