© 2009 The International Society for the Study of Behavioural Development

The peer context in which a child is embedded has a substan-tial influence on his or her social development (Cairns, Xie, & Leung, 1998). For example, individuals ’ social behaviors as well as perceptions of self and others are shaped through inter-actions in their peer group (Brown & Lohr, 1987; Cairns, Leung, & Cairns, 1995). Beginning in middle childhood, children tend to form exclusive peer affiliations called “cliques ” (Crockett, Losoff, & Petersen, 1984). Children in a clique are likely to share similar social information and experi-ences, and the interactions between clique members have been found to be frequent, intense, and exclusive (e.g., Gest, Farmer, Cairns, & Xie, 2003). Also, numerous studies have demonstrated that clique members are similar in many social and behavioral characteristics, including aggression, rates of school dropout and early pregnancy, grades, externalizing problems, academic motivation, and internalizing problem