were used to assess internalizing and externalizing problems. The study used the program Kliquefinder to identify clique membership status through social network analysis. Through use of behavioural descriptions on the Pupil Evaluation Inventory (PEI), peer nominations of externalizing and internalizing behaviors were obtained. Through this study, Witvliet, van Lier, Brendgen, Koot, and Vitaro noted that externalizing problems increased among clique members. They found that clique members compared with isolated children showed, on average, an increase in externalizing problems across that same period. While no sex differences were found in the link between clique membership status and internalizing problems, the association found between clique membership and an increase in externalizing problems was specific to boys only. The researchers claimed that these results support the hypothesis that clique membership protects children against developing internalizing problems. Decline of cliques During middle adolescence, the social norms that once enforced sex cleavage shift to encourage mixed-sex socialization. Single-sex cliques begin to seek out the company of opposite-sex cliques, although at first almost all direct interaction remains within the individual cliques despite the presence of the other clique(s). Gradually, intersex relationships and mixed sex cliques develop, closely followed by the first romantic relationships, which typically appear among early-pubertal, high-status, more physically developed adolescents. Over the course of late adolescence romantic relationships replace clique hierarchies as the most potent determinants of social status and networks of dating couples eventually replace more rigidly structured cliques. The chronological relationship between changing gender dynamics and the dissolution of organized, hierarchical cliques is well-established, but not fully understood. One theory asserts that sex cleavage both arises and wanes because cliques are largely sorted by common interests: girls and boys are generally interested in different activities until dating emerges, after which they share a highly valued activity.(164) This idea is consistent with the direct relationship between pubertal development and the appearance of other-sex friends. One possible explanation for this progression argues that children are socialized from childhood to conform to gender roles and during early adolescence cognitive developments promote active self-presentation and anxiety over peer-perceptions; as a result, early adolescents become more consciously aware of both the benefits of conventional gender identity and the threat of ridicule or rejection in response to unorthodox behavior. According to this framework, gender segregation subsides because the same inculcated gender roles that prompt children to distance themselves from anything associated with the opposite sex also encourage