Background: The federal government and many states have published hospital-specific data on resource use and outcomes of care. Both Pennsylvania and New York State have published data that identify physicians by name. These data are being released without a clear understanding of physicians' responsibilities and the impact of their behavior on patient outcomes. They also lack the clinical specificity necessary for appropriate comparisons of outcomes or processes of care. This article proposes a model for defining the responsibilities of physicians in providing medical care and describes a clinically specific approach to classifying patients for evaluation studies. A proposed model: Physicians' responsibilities require that they act as clinicians, managers, and teachers. Outcomes are affected by many factors-the practices of the individual physician, the contributions of the patient, the setting in which care is provided, and the social and physical environment. To enable clinically specific comparisons to be made, an approach to defining biological severity of illness based on the dimensions of location, etiology, and severity of the problem is described. Conclusion: Public release of data concerning quality of medical care implies a responsibility for the quality of the data being presented. Research needs to be performed to improve measurement tools, new personnel need to be adequately trained, and data that have clinical and statistical validity need to collected and analyzed.