The extent to which testosterone and other androgens might affect cognitive skills in women is not yet well understood. In this chapter, Sherwin reviews changes in endogenous androgens over a woman's lifespan and research findings germane to androgens and cognitive skills in women. For younger women, there is evidence that cyclical changes during the menstrual cycle affect cognitive performance, although it is not possible to tease out effects of testosterone from those of estradiol. In older women, the relation between testosterone levels and cognitive test scores is inconsistent. The ratio of estradiol to testosterone may be important in modulating sex-advantaged cognitive functions in women, with a lower ratio leading to relatively impaired performance on cognitive tasks in which women typically excel.