In the recent literature, the presence of thought disorder occurring with depression has been both supported and contradicted. In order to clarify the relationship of thought disorder and depression this study examined three areas of cognitive function in depressed and non-depressed groups drawn from pain patients and normals. Subjectively, depressed subjects had significant deficits in abstraction, associative tightness, and speed of information processing. Across all subjects, increasing cognitive impairment in all three dimensions correlated significantly with increasing severity of depression. Pain per se and analgesics did not account for the results. There were several significant correlations between the cognitive measures, suggesting a general process mediating the thought disorder associated with increasing levels of depression. The results support and extend the known relationship of thought disorder and depression.