We compared the Social Security Administration's (SSA) judgment of disability with uninvolved rheumatologists' evaluations of ability to work. With the cooperation of the SSA, 52 new disability claimants who alleged rheumatoid arthritis, osteoarthritis, or systemic lupus erythematosus were identified at the beginning of their claim. At the same time that their claim was being formally reviewed, they had a standardized examination by an independent rheumatologist who was not involved with their care, and they had a standardized test of observed performance. Rheumatologists' judgments of ability to work were compared with the SSA judgments. Rheumatologist and SSA judgments were in agreement for 35 of the 52 claimants (67%). All 11 claimants who met or equaled the SSA medical evaluation criteria were judged work-disabled by the rheumatologist. Of 27 judged able to work by the SSA, the rheumatologist judged 11 to be unable. Agreement between the SSA judgment of residual functional capacity and observed performance was no more than would be expected by chance. Most SSA judgments agree with a clinician's evaluation but a standardized physical evaluation by a rheumatologist and performance-based tests appear to add important information.