Public health officials and the communities they serve need to: identify priority health problems; formulate effective health policies; respond to public health emergencies; select, implement, and evaluate cost-effective interventions to prevent and control disease and injury; and allocate human and financial resources. Despite agreement that rational, data-based decisions will lead to improved health outcomes, many public health decisions appear to be made intuitively or politically. During 1991-1996, the US Centers for Disease Control and Prevention implemented the US Agency for International Development funded Data for Decision-Making (DDM) Project. DDM goals were to: (a) strengthen the capacity of decision makers to identify data needs for solving problems and to interpret and use data appropriately for public health decisions; (b) enhance the capacity of technical advisors to provide valid, essential, and timely data to decision makers clearly and effectively; and (c) strengthen health information systems (HISs) to facilitate the collection, analysis, reporting, presentation, and use of data at local, district, regional, and national levels. Assessments were conducted to identify important health problems, problem-driven implementation plans with data-based solutions as objectives were developed, interdisciplinary, in-service training programs for mid-level policy makers, program managers, and technical advisors in applied epidemiology, management and leadership, communications, economic evaluation, and HISs were designed and implemented, national staff were trained in the refinement of HISs to improve access to essential data from multiple sources, and the effectiveness of the strategy was evaluated. This strategy was tested in Bolivia, Cameroon, Mexico, and the Philippines, where decentralization of health services led to a need to strengthen the capacity of policy makers and health officers at sub-national levels to use information more effectively. Results showed that the DDM strategy improved evidence-based public health. Subsequently, DDM concepts and practices have been institutionalized in participating countries and at CDC.