Exp 1 used an infant-controlled habituation procedure to assess 80 5-, 7-, 9-, and 12-mo-old infants’ ability to discriminate pictures of adult male and female faces categorically. The 9-and 12-mo-old groups habituated to a series of male or female faces, generalized habituation to a new face of the same sex, and dishabituated when shown an opposite-sex face, thus showing discrimination of male and female faces as separate categories. In Exp 2, the stimuli were altered so that 3 groups of 12-mo-olds (60 Ss in all) saw men and women pictured with unisex clothing, women pictured with short hair, or women pictured with short hair and both sexes pictured with unisex clothing. Decrements in categorical responding were significant only when both hair and clothing were altered. Individually, a proportion of Ss in each group demonstrated categorical recognition of male and female faces despite changes in stimuli.