In a second follow-up study of sibling interaction, 24 pairs of same-sex siblings and 24 pairs of mixed-sex siblings were observed in their homes 18 months after the first follow-up and 3 years after the initial observations. The patterning of interaction was similar to that observed earlier. (Author/DR)

The expansion process of the family after the arrival of a second child was the focus of this longitudinal study. Sixteen families, each with one child between one and three years old and a second child born at the beginning of the study, were observed in everyday situations when one or both parents were interacting with one or both children.…