In order to determine whether the Mini-Mental State Examination (MMSE) assesses multiple areas of cognitive functioning, a grade of membership analysis, carried out initially on data from a representative sample of community residents, was repeated on data from 718 carefully characterized Alzheimer's disease (AD) cases. The findings from both normal and demented samples differed little. In AD cases three pure types were identified which varied in level of cognitive impairment rather than by aspect of cognitive functioning. The presence of the originally proposed five aspects of cognitive functioning was not confirmed, although subsets (selected orientation items; three recall items; the two naming items) were identified. Nevertheless, since problems with learning and recall are a function of AD, and may underlie ability to respond to the items of the MMSE, summary MMSE score may be a sound indicator of severity of cognitive impairment, even if specific areas of cognitive functioning cannot be identified.