The goal of the proposed research is to investigate the associations between children's sibling relationships and their friendships, peer relationships and adjustment. Indices of adjustment will include self esteem, behavior problems, depressive mood and school achievement. The sample will include 75 first-graders and their older siblings and best friends. Subjects will be visited in their homes where children will be videotaped interacting with their siblings, mothers and best friends. Children and parents will be interviewed about the child's relationships and patents wand teachers will complete questionnaires about children's temperament., behavior problems and peer relationships. The proposed investigation will further our understanding of the role of sibling relationships in children's development by investigating links between sibling relationships and children's adjustment and relationships outside the family.