The major objective of this research is to develop a methodological framework to help analyze the use of resources in ambulatory care environments. Emphasis is placed on trying to understand reasons for variation in treatment patterns. Important methodological considerations include: 1) the selection of a set of medical problems appropriate for evaluating the interaction effects of the variables being considered; 2) the development of problem-specific computerized routines for defining episodes of care based on patient visit information; and 3) the selection of appropriate measures of utilization. The Frontier Nursing Service (FNS) was used as a study setting. FNS is a primary health care service and training center located in Leslie County in eastern Kentucky, an area that covers 1, 000 square miles with a population of approximately 15, 000. The analysis indicates that for common primary care problems, the level of provider training as well as accessibility of services signficantly influence patterns of care.