The effect of stimulus prefamiliarization on children's discrimination learning was investigated. Kindergartners were prefamiliarized with pictures which were identical, similar, or unrelated to pictures used in the learning task. Consistent with predictions derived from previous research, the learning of subjects who were prefamiliarized with unrelated pictures was superior to that of subjects who were prefamiliarized with identical pictures. In addition, improvement over trials in the similar picture condition resembled that of the unrelated (rather than identical) picture conditions, thereby suggesting that the particular pictorial representations of the experimental materials are at least partially responsible for the effect. (Author/CS)