The authors investigated the relation of educational attainment, husband's education, household income, and childhood socioeconomic status to cognitive function and decline among community-dwelling women aged 70-79 years. Information on exposures was self-reported, except for income (which was derived from census tract data). Between 1995 and 2000, six cognitive tests were administered to 19,319 Nurses' Health Study participants. Second assessments began in 2001 and are ongoing; as of April 2002, information was complete for 15,594 women. The authors used logistic regression to calculate multivariate-adjusted odds of a low baseline score (bottom 10%) and substantial decline (worst 10%), and linear regression was used to estimate adjusted mean differences in score and in decline across various levels of education and socioeconomic status. On a global score combining the results of all tests, women with a graduate degree had significantly decreased odds of a low baseline score (odds ratio = 0.49, 95% confidence interval: 0.36, 0.66) and decline (odds ratio = 0.65, 95% confidence interval: 0.50, 0.86) in comparison with women with a Registered Nurse diploma. Significantly lower mean scores and less mean decline were observed among women with a bachelor's or graduate degree than among women with a Registered Nurse diploma. Much weaker associations were evident for other socioeconomic variables. Thus, among well-educated women, educational attainment predicted cognitive function and decline, although other measures of socioeconomic status had little relation.