Longitudinal associations between sibling relationship quality, parental differential treatment, and children's adjustment.

This study examined associations between changes in sibling relationships and changes in parental differential treatment and corresponding changes in children's adjustment. One hundred thirty-three families were assessed at 3 time points. Parents rated children's externalizing problems, and children reported on sibling relationship quality, parental differential treatment, and depressive symptoms. On average, older siblings were 10, 12, and 16 years old, and younger siblings were 8, 10, and 14 years old at Waves 1, 2, and 3, respectively. Results from hierarchical linear modeling indicated that as sibling relationships improved over time, children's depressive symptoms decreased over time. In addition, as children were less favored over their siblings over time, children's externalizing problems increased over time. Findings highlight the developmental interplay between the sibling context and children's adjustment.