Sixty 4-year-old children from two socioeconomic levels were run in a three-phase experiment designed to investigate the effect of Phase 1 training upon the acquisition of stimulus control by two stimulus dimensions. Phase 1 consisted of three different training conditions; one stimulus dimension was correlated with reinforcement, and the second stimulus dimension was: (a) also correlated with reinforcement, (b) uncorrelated with reinforcement, or (c) held constant. In Phase 2, all subjects received reinforcement correlated with both dimensions. In Phase 3, the two dimensions were tested conjunctively, disjunctively, and separately. The results showed that stimulus control was more dependent upon Phase 1 training in children from the higher s!)Cioeconomic level and was more dependent upon a priori preferences in children from the lower socioeconomic level.