The current reliance on linguistic data for inferences about the concept–word relationship has led to serious questions being raised regarding the existence and facilitative role of prelinguistic categories in early word learning. In three experiments a multiple habituation paradigm was used to examine the ability of 7- and 9-month-old prelinguistic infants to form a natural, basic-level object category. In Experiment 1, 9-month-old infants appeared to form a category of bird, but only when habituated to prototypical exemplars as opposed to poor exemplars. Discriminability between prototypical habituation exemplars and test stimuli was demonstrated in Experiment 2. In Experiment 3, 7-month-olds did not form a category of bird when habituated to prototypes. These findings constitute independent evidence for the existence of a linguistically relevant nonlinguistic category prior to the onset of word comprehension. Moreover, formation of prelinguistic categories appears to be facilitated by exposure to prototypes. Such goodness-of-exemplar effects suggest a structural similarity between infants' prelinguistic categories and early semantic categories. Finally, nonlinguistic categorization of natural basic-level objects, as represented in line drawings, appears to emerge between 0;7 and 0;9.