The Smallpox Pre-Event Vaccination Program (SPVP) for public health and hospital-based health care workers began on January 24, 2003. This report summarizes efforts made by health officials in Florida, Nebraska, New Jersey, and Tennessee to facilitate the voluntary participation of acute care hospitals in the SPVP. Seven common characteristics contributed to the success of programs in these four states: (1) early planning, building on existing competencies, and state government support, (2) carrying the program forward on a planned timeline with experienced vaccination staff, (3) use of multifaceted training activities, (4) use of mock scenarios and field exercises to avoid early problems, (5) establishment and fostering of good relationships and lines of communication with stakeholders and the mass media, (6) addressing liability and workers' compensation concerns prior to initiation of the SPVP, and (7) attention to vaccination clinic logistics.