To assess the effect of perinatal environment on adult reproductive behavior, masculine and feminine sexual behaviors of offspring from group-housed C57BL/6J parental females were compared to behaviors of offspring from control parental females housed in male/female pairs. Female offspring born to and raised by previously group housed parental females were less sexually receptive following ovariectomy and hormone replacement than offspring of control parental females. Male offspring born to and raised by previously group-housed parental females exhibited shorter latencies to ejaculation and shorter anogenital distances than offspring of control parental females. Fostering and cross-fostering, procedures to control for the effects of group-housing on maternal behavior, both increased the frequency of abnormal scrotal sacs. Group housing during pregnancy alters the adult reproductive behavior of the offspring. The reduction of receptivity in female offspring could play a role in cyclical changes in population density of confined groups.