While hospital quality evaluation activities have progressed dramatically in recent years, there has not been a comparable development and implementation of methods for the review and evaluation of ambulatory health care. Various technical problems regarding ambulatory records and the nature of ambulatory care itself have combined to retard the evolution of review methods. These problems are discussed, as are current efforts to overcome them. We have reviewed the relevant issues and literature and have attempted to provide a conceptual framework for better understanding the measurement of ambulatory health care quality. A selective bibliography of literature relating specifically to ambulatory care quality evaluation is presented as a guide to further study.