Magnusson (1988) and Brofenbrenner (1979) state that the social environment in which a person is inserted is essential in the study of his behavior. The theoretical framework of developmental and life course theories of crime allows for the addition of the dynamic element of time and places emphasis on the longitudinal processes of how the interaction between the individual and his or her social environment limits and influences the behavior. This longitudinal perspective opens up the possibility that the social environment of peers is dynamic. Friendships can be added and discontinued, resulting in changes in the number of friends reported from childhood to adolescence. Children's transition from intimate elementary classroom environments to a broader age range of adolescents in middle and high school increases the potential for developing friendships with older adolescents. At the same time, the quality of relationships with these friends may also change. Adolescent relationships are becoming more intimate than those of childhood, and sharing intimate feelings and awareness of the needs of others are becoming an important feature of friendship during adolescence. However, although various aspects of the peer social environment may undergo transition and change during adolescence, it is also during this period that friendships are hypothesized to become the most important social context in which an adolescent functions. As a result, time spent in the social environment of peers takes up the majority of an adolescent's day (Csikszentmihalyi and Larson 1984). If this is the case, a natural question to ask is: What happens to the pattern of influence peers have on delinquent outcomes during adolescence? According to life course theory, peers will have a significant influence on delinquent behavior in early adolescence, and this influence grows as the primary social environment in which an adolescent functions shifts from parents to peer networks, but then declines. in late adolescence when there is a shift towards greater commitment to conventional activities. This explicitly indicates a changing pattern of influence within the social institution of peers. Peer Influence on Delinquency During Adolescence Much of the prior research on the age-varying influence of peers on delinquency during adolescence is based on cross-sectional studies that do not explore variation in influence. throughout the adolescent period. It is therefore difficult to identify a recognizable pattern of influence.