Outcomes research represents an expansion of traditional clinical research to include issues of cost and quality of care in usual clinical practice, emphasizing outcomes that matter most to patients. In low back disorders, outcomes research has focused on the lack of reliable information to support much of clinical practice and has demonstrated marked variability in the treatment of these common problems. The Maine Lumbar Spine Study represents an example of an outcomes research study to investigate the treatment of patients with sciatica in usual clinical practice. Because low back symptoms are a frequent cause of occupational disability, Workers' Compensation patients were explicitly oversampled. Baseline features were significantly different in those patients who were receiving Workers' Compensation versus those who were not. Efforts to compare outcomes by disability status need to control for these differences. Whereas most Workers' Compensation patients were still receiving disability compensation regardless of treatment at 6 months, patients who were treated surgically were more likely to have come off disability and returned to work than nonsurgically treated patients. Long-term follow-up is necessary to determine whether these differences persist.