There is an increasing need to plan and assess cancer control programs based on quantitative data. In this paper a model is presented to help planners design cancer control programs to meet the needs of defined high-risk populations. This model can be applied to demographically defined segments of the U.S. population, to geographically defined populations, and to demographic subpopulations within geographically defined areas. It is intended to allow planners to assess the cancer control needs of high risk populations in terms of lowering cancer risks using available primary and secondary prevention techniques. This model represents only one of many quantitative factors that should be integrated into planning cancer control activities.