Eight experiments were performed to determine the perceptual cues used by 3- and 4-month-old infants to categorically distinguish between perceptually similar natural animal species. These experiments provided evidence that information from the facial and head region, specifically, the internal features of the face and the external contour of the head, give the infant a necessary and sufficient basis to form a categorical representation for cats that excludes dogs. The results are discussed in terms of Johnson and Morton's (1991) theory of facial recognition and more general accounts of the information underlying categorical representations.