Protecting public health requires the acquisition, use, and storage of extensive health-related information about individuals. The electronic accumulation and exchange of personal data promises significant public health benefits but also threatens individual privacy; breaches of privacy can lead to individual discrimination in employment, insurance, and government programs. Individuals concerned about privacy invasions may avoid clinical or public health tests, treatments, or research. Although individual privacy protections are critical, comprehensive federal privacy protections do not adequately protect public health data, and existing state privacy laws are inconsistent and fragmented. The Model State Public Health Privacy Act provides strong privacy safeguards for public health data while preserving the ability of state and local public health departments to act for the common good.