Patterns of cognitive activity, and their relation to cognitive function, were examined in a geographically defined, biracial population of persons aged 65 years and older. Persons (N = 6,162) were given cognitive performance tests and interviewed about their participation in common cognitive activities, like reading a newspaper. Overall, more frequent participation in cognitive activities was associated with younger age, more education, higher family income, female gender, and White race; participation in activities judged to be more cognitively intense was not strongly related to age, but was associated with more education, higher family income, male gender, and White race. Substantial heterogeneity in activity patterns remained after accounting for demographic factors, however. In an analysis controlling for demographic variables, level of cognitive function on performance tests was positively related to composite measures of the frequency and intensity of cognitive activity. Longitudinal studies are needed to assess the relation of cognitive activity patterns to stability and change in cognitive function in older persons.