This article documents the instability and variation in public financing of public health functions at the federal and state levels. Trust for America's Health has charted federal funding for the Centers of Disease Control and Prevention, which in turn provides a major portion of financing for state and local public health departments, and has compiled information about state-generated revenue commitments to public health activities nationwide. The federal-level analysis shows that funding has been marked by diminished support for "core" public health functions. The state-level analysis shows tremendous variation in use of state revenues to support public health functions. The combination of these factors results in very different public health capacities across the country, potentially leaving some states more vulnerable, while simultaneously posing a general threat to the nation since public health problems do not honor state borders. On the basis of this analysis, the authors suggest changes in the financing arrangements for public health, designed to assure a more stable funding stream for core public health functions and a more consistent approach to financing public health activities across the country.