It is widely recognized that peer-directed aggression and victimization are pervasive social problems that impact school-aged children and adolescents. This study investigated the developmental course of aggression and victimization, and more specifically, addressed three primary aims. First, distinct subgroups of children were identified based on similarities and differences in their physical, verbal and relational aggression and victimization. Second, developmental stability (and instability) were assessed by examining the extent to which individuals remain (or change) subgroups throughout childhood and adolescence. Third, group classifications and transitions over time were assessed as a function of children’s individual characteristics and their relational and contextual experiences.

The sample for this longitudinal study consisted of 482 children (50% females) who were followed over time from grades 1 to 11. Multiple-informant data on children’s physical, verbal and relational aggression and victimization (peer-reports), individual characteristics including emotion dysregulation, withdrawn behaviors (teacher-reports), and hostile and self-blaming attributions (self-reports), and their relational and contextual experiences including peer rejection, friendships, social hierarchy and classroom aggression (peer-reports) were assessed in grades 1, 5, 8, and 11. Data analyses primarily consisted of a series of person-centered methods including latent profile and latent transition analyses.

Most of the identified subgroups (e.g., aggressors, victims and aggressive-victims) were distinguishable by their frequencies (i.e., levels) of aggression and victimization, rather than forms (physical, verbal and relational), with the exception of one group that appeared to be more form-specific (i.e., relational aggressive-victims). Among children in each group there was a modest degree of intra-individual stability, and findings elucidated how some groups appeared to be more stable than others as well as developmental differences. Although group stability was fairly common across all groups, and over time, patterns of instability also emerged.

The combination of trends reflecting both stability and instability support the perspective that the development of aggression in childhood and adolescence is characterized by heterogeneity. In contrast to perspectives that highlight the individual stability of aggression (e.g., that it is a stable behavioral style or individual disposition), findings elucidate the individual, relational and contextual mechanisms by which developmental stability and instability were more pronounced.

This study examined the influence of childhood aggression, peer exclusion and associating with deviant peers on the development of antisocial behavior in early adolescence. To gain a stronger understanding of how these factors are associated with antisocial behavior and delinquency, multiple alternative pathways were examined based on additive, mediation and incidental models. A parallel process growth model was specified to assess whether early childhood aggression and peer exclusion (in 1st grade) and intra-individual increases in aggressive behaviors and exclusion through childhood (grades 1 to 6) are predictive of associating with deviant peers (in 7th grade) and antisocial behavior (in 8th grade). Based on a sample of 383 children (193 girls and 190 boys), results showed the strongest support for an additive effects model in which early childhood aggression, increases in aggression, increases in peer exclusion and associating with more deviant peers all predicted antisocial behavior. These findings have implications for how children's psychological adjustment is impacted by their behavioral propensities and peer relational context and the importance of examining developmental processes within and between children over time.