A cross-sectional study was conducted on functional status of adults visiting primary care practices. Limitations in physical and mental function were assessed independently in 28 practices by patients (N = 1,227) and physicians (N = 47) using a simple global index of disability. Results indicated 12% of patients rated their physical limitations as major and 8% rated major emotional limitations during the past month. Comparable assessments by physicians were 5% and 4%, respectively. Differences between patients and physicians were statistically significant and are demonstrated to be clinically relevant. Patients' functional limitations were associated with increased utilization of ambulatory care, older age, lower level of education, unemployment, and a primary diagnosis of a chronic condition. We conclude that functional status can be routinely recorded in medical practice to help describe severity, predict utilization, and improve the physician-patient relationship.