• indirect aggression;
  • trajectories;
  • predictors;
  • longitudinal study;
  • early childhood;
  • population based study;
  • sex differences


The purposes of this study were to model the development of indirect aggression among a nationally representative sample of 1,401 Canadian children aged 4 at T2, 6 at T3, 8 at T4 and 10 at T5, and to examine predictors of trajectory group membership from T1 (age 2) child, familial, and parenting variables. Using a semi-parametric group-based modeling approach, two distinct trajectories were identified: “increasing users” comprising of 35% of the sample and “stable low users” comprising of 65% of the sample. Using logistic regression analyses to distinguish these two groups, we found that for girls, more frequent, increasing use of indirect aggression was associated with prior prosocial and physically aggressive behavior, low SES and low parental social support at age 2. For boys, increasing use of indirect aggression was associated with prior parenting issues at age 2—inconsistency and less positive parent–child interactions. Although this study provides unique information regarding the early development of indirect aggression and its predictors, more longitudinal research is needed to fully understand its development. Aggr. Behav. 33:314–326, 2007. © 2007 Wiley-Liss, Inc.