How do words affect categorization? According to one theoretical account, even early in development, labels are category markers and are different from other features. According to another theory, early in development, labels are part of the input and are no more than other features. The current study addressed this issue by examining the effects of labels on category learning in 8- to 12- month infants. Infants were familiarized with exemplars from one category in either label-defined or motion-defined condition and then tested with prototypes from learned category and novel category. Eye tracking results indicated that infants exhibited better category learning in the motion-defined than in the label-defined condition. These results provide little evidence for the idea that labels are category markers that facilitate category learning.