This study examined the effects of stimulus differentiation on kindergartners' ability to coordinate spatial perspectives when classified by conceptual tempo. 33 children were asked to identify from an array of pictures the one which best represented a doll's view of the stimulus display. Two stimulus displays were constructed which differed in the degree of differentiation among their items. In one set, low differentiation, three three-dimensional cardboard forms were in the shape of houses, each house having minimal external cues. In the second set, high differentiation, were three three-dimensional house scenes with each house having numerous external cues. The subjects took longer to make an initial response, made more correct, and somewhat fewer egocentric responses under the high differentiation condition than under the low differentiation condition. There also was an interaction between conceptual tempo and environmental differentiation; the impulsive children's egocentric performances were more influenced by the stimulus conditions than were the reflective children's. These findings suggested that organismic and environmental conditions are both important factors in children's spatial cognition.