This study examined the characteristics of the child's social network as it changes within the preschool period. Of particular interest is how the social network changes as the child moves from a more home-centered existence at 3 years to a more school-centered existence at 6 years of age. Also of concern is the effect of sex and socioeconomic status on the nature of the child's social network. A total of 85 children and their mothers were studied as part of a longitudinal research project. Each mother reported on their child's contacts with relatives, adults, and peers when the child was 3 and 6 years old. The results show that the child's social network composition and contacts change with age and vary as a function of the child's sex and socioeconomic status. For example, from 3 to 6 years children decrease contact with relatives and increase contact with peers and non-relative adults. Across age, but especially at 6 years of age, male subjects have more contact with male than female friends and female subjects have more contact with female than male friends. These findings illustrate how sex role socialization patterns are reflected in contact with same sex peers compared to opposite sex peers in the social network. In general, the findings suggest that the social network structure provides different types of interaction opportunities according to developmental level as well as sex and socioeconomic status of the child. (Author/RH)