title: Developmental Trajectories of Peer-Reported Aggressive Behavior: The Role of Friendship Understanding, Friendship Quality, and Friends' Aggressive Behavior.
abstract: OBJECTIVE
  To investigate developmental trajectories in peer-reported aggressive behavior across the transition from elementary-to-middle school, and whether aggressive behavior trajectories were associated with friendship quality, friends' aggressive behavior, and the ways in which children think about their friendships.
  
  
  METHODS
  Participants included a community sample of 230 5thgrade children who were assessed when they made a transition from elementary-to-middle school (6thgrade). Peer nominations were used to assess the target child's and friend's aggressive behavior. Self- and friend reports were used to measure friendship quality; friendship understanding was assessed via a structured interview.
  
  
  RESULTS
  General Growth Mixture Modeling (GGMM) revealed three distinct trajectories of peer-reported aggressive behavior across the school transition: low-stable, decreasing, and increasing. Adolescents' understanding of friendship formation differentiated the decreasing from the low-stable aggressive behavior trajectories, and the understanding of friendship trust differentiated the increasing from the low-stable aggressive and decreasing aggressive behavior trajectories.
  
  
  CONCLUSIONS
  The findings indicated that a sophisticated understanding of friendship may serve as a protective factor for initially aggressive adolescents as they transition into middle school. Promoting a deepened understanding of friendship relations and their role in one's own and others' well-being may serve as an important prevention and intervention strategy to reduce aggressive behavior.
authors.affiliation: University of Toronto.
authors.forename: Tina
authors.initials: T
authors.lastname: Malti
authors.affiliation: University of Alabama.
authors.forename: Kristina
authors.initials: K
authors.lastname: McDonald
authors.affiliation: University of Maryland.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Rubin
authors.affiliation: Brock University.
authors.forename: Linda
authors.initials: L
authors.lastname: Rose-Krasnor
authors.affiliation: University of Washington.
authors.forename: Cathryn
authors.initials: C
authors.lastname: Booth-LaForce
keywords: aggressive behavior; developmental trajectories; friendship quality; friendship understanding; protective factors