HAVING COME TO THE STUDY OF NEONATES BY WAY OF PEDIATRIC practice and psychoanalytic research on mother-infant interaction at the Putnam Children's Center, we became aware of the powerful influence of the individuality of the new infant in shaping his environment.1 In the early 1950s, when most of our research was aimed at understanding the environmental forces which produced pathology in childhood, we were struck with the importance of seeing this pathology as the result of an interaction between the child and his environment. It appeared to be vitally important to understand why parents could function well with one kind of infant but not with another (Brazelton, 1976). This led us to try to