Health planning involves assessing health care needs of a defined population, setting priorities, then developing, implementing, and evaluating programs that address priority needs. The concepts of health planning are central to the 1988 report of the Institute of Medicine on the Future of Public Health, which defmed the three core functions of public health as assessment, policy development, and assurance. Generally, when health planning is instituted, poor people are identified as having the poorest health status and the greatest need. An internal ethic is therefore created for public health to focus on the health care needs of those in poverty. This internal ethic of public health can become the driving force for reforming the present U.S. health care system. A reformed health care system would be guided by the principle of care according to need, which not only has a basis in health planning, but in social justice as well. © 1996 Taylor & Francis Group, LLC.