Abstract
From late childhood, friendships as a distinct peer experience become increasingly salient in affecting individual development. This one-year longitudinal study examined same-domain and cross-domain effects of aggression and depression in friendships among early adolescents in China. Participants included 226 students (95 boys) within 113 friendship dyads initially in sixth grade (initial mean age = 12 years) in two public junior high schools. Data on aggression, depression, and friendship were collected from self-reports and peer nominations in 2017 and 2018. The results using the actor-partner interdependence model showed that friends’ aggression positively predicted adolescents’ later aggression and that friends’ depression positively predicted adolescents’ later depression, indicating same-domain contagion effects. In addition, friends’ aggression positively predicted adolescents’ later depression, indicating cross-domain cascading effects. The results suggest that adolescents with more aggressive friends are at risk for developing higher levels of social-behavioral and psychological problems with time. The results help understand the role of friendships in individual maladaptive development and are discussed in terms of the Chinese context.