Numerous studies have provided evidence that both human and nonhuman males reliably outperform females on tasks that require spatial ability. Because most of the research on this topic has utilized hormonally normal adults as subjects, it is still not known to what extent, if any, sex differences in spatial ability can be attributed to hormonally organized dimorphisms in neural structures subserving cognitive function. The purpose of this paper is to address this critical issue in three areas: (1) Research that demonstrates that male rodents initially outperform females on maze tasks that utilize visuospatial representation will be reviewed. (2) New data which provide strong evidence for the organizational effects of gonadal steroids will be described. The timing of the sensitive period for hormone action, the specific hormones involved and their possible sites of action will be discussed. (3) The question of what behavioral processes hormones might be affecting to cause differential performance on spatial tasks will be examined. The studies described in this review suggest that gonadal steroids, probably the testosterone metabolite estradiol, cause organizational effects during perinatal development which have multiple effects on the associational-perceptual-motor biases that guide visuospatial navigation.