Although physicians' communication style and perceptions affect outcomes, few studies have examined how these perceptions relate to the way physicians communicate with patients. Moreover, while any number of factors may affect the communication process, few studies have analyzed these effects collectively in order to identify the most powerful influences on physician communication and perceptions. Adopting an ecological approach, this investigation examined: (a) the relationships of physicians' patient-centered communication (informative, supportive, partnership-building) and affect (positive, contentious) on their perceptions of the patient, and (b) the degree to which communication and perceptions were affected by the physicians' characteristics, patients' demographic characteristics, physician-patient concordance, and the patient's communication. Physicians (N=29) and patients (N=207) from 10 outpatient settings in the United States participated in the study. From audio-recordings of these visits, coders rated the physicians' communication and affect as well as the patients' participation and affect. Doctors were more patient-centered with patients they perceived as better communicators, more satisfied, and more likely to adhere. Physicians displayed more patient-centered communication and more favorably perceived patients who expressed positive affect, were more involved, and who were less contentious. Physicians were more contentious with black patients, whom they also perceived as less effective communicators and less satisfied. Finally, physicians who reported a patient-centered orientation to the doctor-patient relationship also were more patient-centered in their communication. The results suggest that reciprocity and mutual influence have a strong effect on these interactions in that more positive (or negative) communication from one participant leads to similar responses from the other. Physicians' encounters with black patients revealed communicative difficulties that may lower quality of care for these patients.