Individual differences in the social behavior of young siblings were studied in 40 sibling pairs observed at home, when the second child was 8 months old and 14 months old. Differences between same-sex and different-sex sibling pairs were marked by the second observation. More positive social behavior characterized same-sex pairs; more negative…

Part of a longitudinal study of women and their first-born children who have different employment and day care experiences during the children's first three years of life, this study focuses on the socioemotional development of children at 18 months of age, who had received at least nine months of continuous day care. Particular attention is given…