The nature and extent of possible age-related changes in cognitive function have primarily been examined in nonrandom samples, and have not been well described in population-based studies. We examined longitudinal changes in performance on a mental status examination and recall and recognition memory tests in a population-based (n = 1953) study of community-dwelling elders. Advanced age was associated with poorer performance on all tests and more rapid decline longitudinally on the mental status and recall and recognition memory tests. Less-educated persons performed more poorly. Lower levels of educational attainment were predictive of more rapid declines on the mental status examination and recall memory test among women. Subsequent survivorship was associated with preserved performance on the mental status and recall memory tests. These findings suggest that there are age-associated changes in cognitive function, and have implications for population-based studies of cognitive function and survey research in general.