The Infant-Infant Contact Code, developed to observe the social behavior in infants, is described. Results from using this scale with nine infants under nine months indicated that contacts between infants are complex in nature, that there are developmental changes in models of encounter, and that babies take different roles in relation to the contact. Differences between baby-adult and baby-baby interactions were noted. In baby-baby interactions, both social and non-social behaviors were present. With adults, the behaviors were social. It was suggested that the study of peer interactions during the first year of life may provide additional information about the development of social interaction. (SBT)