Most research in the field of scheduling of ambulatory patients has defined outpatient appointment systems along a patient-arrival spacing dimension. Along this dimension, scheduling methods have ranged from pure block systems (in which all patients are asked to arrive before the start of the clinic) to individual appointment-time systems (in which patients are given appointments at intervals which approximate average physician service time). Four factors—type of scheduling system utilized, amount of physician lateness, amount of patient lateness, and patient no-show rate—have been shown to affect patient waiting time strongly. A study performed in the Combined Clinics of the Massachusetts General Hospital and the Massachusetts Eye and Ear Infirmary provides two additional findings with regard to the ambulatory scheduling process. First, the assignment at the time of appointment of a patient to a specific physician is another significant element in the design and the effectiveness of appointment systems. Second, with the addition of the assignment variable in system definition, a striking behavior pattern was found. The no-show rate, patient arrival time, physician arrival time, and patient waiting time all changed in concert from one appointment system to another among three major systems studied. All factors were found to favor the expeditious delivery of patient care by systems which treated the patient as an individual, in comparison with those that implicitly regarded him as an anonymous figure seeing an unidentified physician.