Objective measures of disease activity (erythrocyte sedimentation rate and joint swelling), disease severity (radiographic ratings), and psychological variables (coping strategies and affective states) were used to predict the degree of pain and functional impairment that would be experienced by a group of 53 patients who had rheumatoid arthritis. The severity of disease demonstrated no significant relationship to measures of outcome. Multiple regression analyses revealed that psychological variables explained a substantial proportion of the variance in outcome scores, even after disease activity was taken into account. Our study highlights the discrepancies between biomedical measures of disease severity and activity and patient outcome in a rheumatoid arthritis population, and our observations suggest that some of these discrepancies may be explained by psychological variables.