The results of a study to identify the factors that two types of referring physicians, general/family practitioners and general surgeons, consider when deciding whether or not to refer the patient, and where to refer the patient are presented and discussed. The factors for each type of decision were identified initially through interviews with physicians in active practice in Wisconsin and rank ordered according to their relative importance in making the referral decisions. These factors were then used in two alternative normative decision-making models to predict physician referral behavior. Factors related to the kind and quality of medical care the patient would receive appear to be most important in the decisions, with a high level of agreement between and among general/family practitioners and general surgeons as to the relative importance of the factors. Although the normative decision-making models correctly predicted a relatively high percentage of the referral decisions, not all of the factors were found to be important in explaining the behavior of physicians, and were not always consistent with the factors that were reported to be important.