We asked whether homosexual and heterosexual men and women differ on standard measures of cognitive ability. Subjects were adults recruited for a family study of sexual orientation. They completed the Fy Scale of the California Psychological Inventory, a self-administered measure of psychological "femininity," and were given subtests of the Wechsler Adult Intelligence Scale and the Primary Mental Abilities test which had been previously shown to discriminate between the sexes. We predicted that homosexual subjects would score significantly in the gender-atypical direction on the Fy scale. We also predicted that they would achieve scores on the tests of cognitive abilities significantly in the direction of the other gender. Comparisons were made between homosexual and heterosexual individuals within gender. Also, comparisons were made between heterosexual men and women to see if our results replicate differences typically found between the genders. As predicted, both homosexual men and women were strongly gender-atypical on the Fy scale relative to their heterosexual counterparts. However, neither differed from heterosexuals on any of the measures of cognitive abilities. Heterosexual men did better than women on the Primary Mental Abilities spatial relations test. We conclude that sexual orientation is not related to specific cognitive abilities.