An investigation of the short term stability of infants' responses to strangers was conducted. Ss were 60 randomly chosen full-term family-reared infants, 30 boys and 30 girls, selected to fit into three age groups of 8, 10 and 12 months. The experimental design was such that the order of first, second, and third visits was counter-balanced between experimenters. During the meeting, the S, who was at his feeding table, was observed for facial expression, visual and vocal behavior, as well as his gestures and movements. Every action and expression was scored as Positive, Negative, or Undifferentiated. Results indicate that the majority of the children at the ages investigated have achieved the perceptual, cognitive, and emotional ability to respond differentially to various individuals, and to respond negatively under certain conditions. (CK)