Youngsters' peer relationships and friendships play a critical role in their social/emotional development. From early childhood on, children spend a considerable amount of time with peers (Ellis, Rogoff & Cromer, 1981). For example, prior to the school years, children interact with peers in child care settings, playgroups or preschool programmes. By 6 to 7 years of age, children spend most of their daytime hours in school or play settings with classmates and friends; this trend continues, and accelerates, through adolescence (La Greca & Prinstein, 1999). It is in the context of these peer interactions that children learn how to share and take turns, how to interact with others on an equal basis, and how to place others' concerns before their own. Successful peer relations contribute in positive ways to the development of social skills and feelings of personal competence that are essential for adolescent and adult functioning (Ingersoll, 1989). Indeed, volumes have been written about the developmentally unique and essential social behaviours that develop in the context of children's peer interactions (Asher & Coie, 1990; Hartup, 1996; Newcomb, Bukowski & Pattee, 1993).
Children's peer relations also make a positive contribution to emotional adjustment and well-being. Supportive friendships serve a protective function, such as by moderating youngsters' reactions to disasters (La Greca et al., 1996; Vernberg et al., 1996), and lessening the impact of parental conflict (e.g. Wasserstein & La Greca, 1996). Furthermore, during adolescence, peer relationships are instrumental in facilitating adolescents' sense of personal identity and increasing their independence from family influences (Dusek, 1991; Ingersoll, 1989).