Data from the 1981 East Baltimore Mental Health Survey were used to examine the relationship between cognitive impairment and psychiatric diagnosis in an adult population. The Mini-Mental State Examination was administered to 3841 household respondents and a subset of 810 received psychiatric evaluations. Of the 810, 23% were found to be cognitively impaired. Over one-third of those with cognitive impairment, however, did not meet DSM-III criteria for a psychiatric diagnosis. Education, geographical background, race and neurological status were predictive of cognitive performance. There was no linear effect of age on cognitive performance with disease status and education controlled. In addition to their cognitive impairment these individuals, who ranged in age from 19 to 89, were found to have significant functional disabilities. Cognitive performance itself, along with physical and emptional health, predicted total functional disability.