Two experiments examined infants' ability to form a spatial category when habituated to few (only 2) or many (6) exemplars of a spatial relation. Sixty-four infants of 10 months and 64 infants of 14 months were habituated to dynamic events in which a toy was placed in a consistent spatial relation ("in" or "on") to a referent object. At 10 months, infants formed a spatial category (looking longer at an unfamiliar than familiarized spatial relation) only when habituated to 6 exemplars. At 14 months, infants formed the spatial category regardless of the number of habituation exemplars. The results highlight developmental changes in infant spatial categorization and show that increasing exemplar number facilitates this ability in infants of 10 months. (Contains 3 figures.)