Physical, mental, and social disability are defined. A sociomedical scheme for disability research is presented. How physical and social disability are measured in general health surveys and in arthritis research is described and evaluated. Societal and individual impacts of arthritis are distinguished. The public health importance of arthritis compared with other chronic conditions is portrayed, and the empirical literature on links between arthritis, impairment, physical disability, and social disability is reviewed. Osteoarthritis is at the forefront of the discussion because of its prevalence, but the theoretical and measurement issues presented are broadly relevant for the rheumatic diseases.