It has been 20 years since the last estimate of the public health workforce's size and composition. This study provides a best estimate through secondary analysis of existing workforce reports, summaries, and information gathered from chief health officials in 50 states and 6 territories, public health organizations, and federal agencies. Results indicate that the workforce consists of some 448,254 persons in salaried positions as follows: 44.6 percent professionals, 4 percent officials/administrators, 14 percent technicians, and 13 percent clerical/support. Workforce size may have decreased by as much as 10 percent over the last 20 years, despite a 25 percent increase in population and rising health hazards.