The mission of public health is to promote physical and mental health, prevent disease, injury, and disability, and protect the public from environmental hazards. Public health and health care are interrelated and interdependent. Prior to the early 20th century, when the scientific basis of disease was poorly understood, public health and medicine worked together collaboratively. As the combined efforts of medicine and public health reduced the threat and changed the management of infectious diseases, public health’s mission began to evolve, with increasing emphasis on interventions targeted at individuals as a means of preventing the spread of disease through communities. Now public health emergency preparedness has become an imperative. The existing public health system is extremely complex, both legally and organizationally, resulting in a public health infrastructure that varies widely from State to State and community to community. States must prepare plans that would both assess their current capacity for responding to a public health emergency and detail the actions that would be taken to achieve upgraded capabilities. The following areas are targeted for progress: preparedness planning and readiness assessment, surveillance and epidemiology capacity, laboratory capacity for the diagnosis of biological agents, communications and information technology, communication of health risks and dissemination of health information, and education and training. States must provide a brief description of their existing capacity, an assessment of whether capacity is adequate, and a proposal for effecting improvements in those areas judged to be inadequate. Unprecedented Federal support and oversight may lead to more uniform and robust health preparedness capabilities across the country. 60 endnotes, 2 appendices