Deviant peer affiliation, self-control, and aggression during early adolescence: within-person effects and between-person differences

Abundant studies have explored the relations among deviant peer affiliation, self-control, and aggression without separating within-person from between-person effects. Moreover, it is unclear whether self-control mediates the associations between deviant peer affiliation and aggression during early adolescence. This longitudinal study used Random Intercept Cross-Lagged Panel Model to examine the dynamic relations among deviant peer affiliation, self-control, and aggression within individuals, including examining whether self-control mediated the relations between deviant peer affiliation and aggression. A total of 4078 early adolescents (54% boys, Mage = 9.91, SD = 0.73) completed questionnaires on four occasions across 2 years. Results indicated: (a) Deviant peer affiliation and aggression positively predicted each other; (b) Self-control and aggression negatively predicted each other but were unstable; (c) Deviant peer affiliation and self-control negatively predicted each other; and (d) Self-control mediated the path from aggression to deviant peer affiliation, but not vice versa. The results more precisely identify the relations among deviant peer affiliation, self-control, and aggression within individuals, providing valuable information for prevention and intervention programs targeted at alleviating early adolescent aggression.