Infants respond differentially, and at times with fearlike behavior to unfamiliar persons. This study was designed to see how infants discriminate among strangers. Since it has been shown that infants respond differently to children and adults, the physical characteristics of persons used to make such differentiations were of interest. Facial configuration and height were systematically varied as five different strangers--a male and a female child, a male and a female adult, and a small adult female the same height as the children (midget)--each approached 40 different infants. The infants respond as if there were three classes of persons-adul children, and small adults. Infants as young as seven months of age reacted to the size-facial configuration discrepancy of the small adult condition. (35pp.)