In order to examine the nature of dimensional processing in children, 20 kindergarten and 20 third grade Chinese-American children were asked to make similarity judgments for unidimensional sets of stimuli differing in color (hue), size, and shape, respectively. Age differences were generally confined to the color set. The judgments of the older children were more internally consistent, and more similar to the other children in their age group than were the younger children. The frequency of good-fitting Scaling Solutions was also higher for the older children. The processing of color in a relational manner thus seems to develop more slowly than relational processing of size or shape. Implications of these results are discussed. Forty white kindergarten children also did all three tasks. Results for these children indicated the same sequence of difficulty, although these children were less consistent and sophisticated than the Chinese children. (Author/ED)