Osteoarthritis (OA) is the most common chronic disease affecting older persons. Depending on the method of evaluation and the diagnostic criteria used, estimates of symptomatic disease prevalence range from 50% to 80% of the elderly population. Rheumatoid arthritis affects 1% of the adult population. Half of all disability in older persons has been attributed to arthritis. OA is associated with pain, functional disability, and being homebound. Several studies have demonstrated regional and subspecialty variations in the use of pharmacological, nonpharmacological, and surgical treatment modalities. This article identifies quality indicators (QIs) that may be used to assess the prevention and treatment of OA, investigate the relationship between processes and outcomes of care, and review the available data in support of each of these indicators. METHODS: The methods used to develop these measures are detailed in an accompanying manuscript in this issue.