A central problem in planning primary health care services for a specific target population is to understand how that population reacts to the mix of services provided and the way in which the delivery system is organized. An ability to determine the factors influencing an individual’s decision to seek care would be an important contribution to the management of primary care facilities and the removal of barriers that deny certain portions of a population access to care. An essential feature of this method is the use of a direct measure of a family’s utilization of primary medical services that is simple and inexpensive to construct for a target population. In addition, the analytical techniques employed are sufficiently strong to permit the drawing of predictive relationships and valuable insights. An example based on a community of 3,000 families illustrates the advantages the approach offers for effective regional health services planning.