In this study, we examined sex differences in performance on a variety of cognitive tasks. Performance was correlated with estradiol and testosterone levels in both men and women in order to examine whether hormone levels are related to performance on tasks that do and do not show sex differences. Men showed an advantage in performance on tests of spatial cognition (block design and card rotation) as well as a dart throwing task that requires both motor skills and spatial cognition. Sex differences were not found for measures of verbal and nonverbal memory, verbal fluency, or fine motor performance. Hormone levels were related to performance on tasks that showed sex differences as well as those that did not. Estradiol, but not testosterone, was related to block design in women but not men. Women with higher estradiol levels showed better performance than women with lower estradiol levels. No relations between card rotation and hormone levels were found. Performance on the two spatial cognitive measures were related to each other in women, but not men, suggesting that men may use different processes than women to accomplish these tasks. Performance on the dart throwing task was not consistently related to the spatial cognitive measures in either men or women. Positive relations that will require confirmation were found between estradiol and spatial recall, and between testosterone and verbal recall, in men. In general, both men and women showed a negative relation between both estradiol and testosterone and dart throwing performance. These results do not support the notion that sex differences will necessarily predict the direction of the relation (positive or negative) between estrogen or testosterone and behavior in adulthood.