- There is evidence that family physicians (FPs) reduce health care costs by reducing patient referral to more expensive secondary and tertiary care facilities. Presumably, the effectiveness of FPs in meeting patients' needs is related to their role definition and willingness to assume responsibility. The purpose of this study was to determine the influence of training and practice setting on responsibility taking and role definition of FPs. A previously developed and validated self-administered questionnaire was completed by 153 certified FPs and FP residents from five departments of family practice in Israel. The main independent variables were previous training and practice setting. The main outcome measures were self-reported data on responsibility taking, role boundaries, and reported role performance. The results showed that certified FPs were more willing to assume responsibility, to define broader role boundaries, and to perform more specialized interventions than residents. Differences in practice setting affected only reported performance, with physicians who practice in rural clinics performing more specialized activities than those in urban clinics. Multiple regression analysis shows that professional development is associated with an increased willingness to assume responsibility ; this willingness affects role boundaries definitions, which affects reported performance. Practice setting alters the tendency to perform a wider range of interventions, but does not affect physicians' attitudes.