This study examines cognitive diversity through performance of four attentional tasks and a vocabulary measure in relation to age and level of education. Tasks were performed by 168 participants (aged between 45 and 91 years) who were grouped according to age and level of education. Multivariate analyses of variance were applied to Z scores calculated from intersubject coefficients of variation. When the variance associated with education was discounted prior to analysis, a disproportionate increase in cognitive diversity was observed in participants over 75 years of age. When cognitive diversity was analyzed in relation to age and education in the three youngest age groups, participants with a low level of education displayed higher diversity in most attentional tasks from 66 years of age. In participants with a high level of education, diversity was lower for all attentional tasks considered from 56 years of age. Vocabulary knowledge was the most sensitive to education-related cognitive diversity. The diversifying effect of the relationship between education and diversity on fluid cognitive performance appeared to reverse and become a homogenizing effect with increasing age.