This study investigates the development of multiplicative classification skills in lower class black and middle class white children on tasks which contain either three-dimensional objects or two-dimensional pictorial representations of the same objects. Multiplicative classification refers to the simultaneous classification of objects into two or more categories. A total of 96 subjects were used, 32 from the following age levels: 4:0-4:11 years, 6:0-6:11 years, 8:0-8:11 years, each age group comprising half females and half males. One-half of the subjects (Ss) at each age level were lower class black children; the remainder were middle class white children. A matrix completion task was used. A subject is presented with stimulus objects in the form of a 2x2 matrix with one cell empty. A subject is to choose the object from a choice set that completes the matrix. Two practice matrices and five test matrices were employed. Familiar objects were used. Social class comparisons at each age level for the combined matrix forms indicated no significant difference at either the four-five or six-seven year levels. At the eight-nine year level lower class Ss performed significantly more poorly. There was a significant age by social class interaction effect. (JM)