The authors propose that the sibling relationship offers the child a potentially rich opportunity for experiencing social exchange and solution of interpersonal conflicts. They illustrate this with the example of the development of a four-and-a-half-year-old boy and his two-and-a-half-year-old sister. The older child initially viewed the new baby as one who takes away what he values, but he gradually moderated his aggression. The authors show how this came about. He gradually identified with his parents as caretakers and through a process of expanding empathy