Osteoarthritis is the most common chronic condition affecting older persons. This condition is probably not a single disease but rather "a group of overlapping distinct diseases, which may have different etiologies but with similar biologic, morphologic, and clinical outcomes" A common final result of these diseases, however, is the degeneration of articular cartilage with loss of the joint surface. Depending on the method of evaluation and the diagnostic criteria used, estimates of symptomatic disease prevalence range from 50% to 80% in the elderly population. Half of all disability among older persons has been attributed to arthritis. Osteoarthritis is associated with pain, functional disability (5, 6), and being homebound. Although effective therapies exist to treat this disease, many are associated with substantial toxicities. Several studies have demonstrated regional and subspecialty variations in the use of pharmacologic, nonpharmacologic, and surgical treatments. Indirect evidence suggests that these differences result in variations in outcomes and in quality of care. On the basis of a comprehensive literature review, a set of process indicators to assess the quality of health care for vulnerable elders with osteoarthritis was developed. This paper summarizes the methods used to develop these indicators and reviews the evidence on which they are based. METHODS The methods for developing these quality indicators, including literature review and expert panel consideration, are detailed in a preceding paper (10). For osteoarthritis, the structured literature review identified 6201 titles from which abstracts and articles relevant to this report were identified. Finally, the supporting evidence was supplemented with the author's own extensive files from previous related work and with the recommendations of an external expert reviewer. On the basis of the literature and the author's expertise, 18 potential quality indicators were proposed. The search terms and results of the literature review can be accessed at www.acponline.org/sci-policy/. RESULTS Of the 18 potential quality indicators, 11 were judged valid by the expert panel process (see the quality indicators on pp 653-667) and 7 were not accepted (www.acponline.org/sci-policy/).