Multiple trajectories of physical aggression among adolescent boys and girls.

Latent growth mixture modeling was used to identify discrete patterns of physical aggression from Grades 7 to 11 among a sample of 1,877 youth. Four trajectory classes adequately explained the development of physical aggression in both boys and girls: Low/No Aggression; Persistent High Aggression; Desisting Aggression, characterized by decreasing risk throughout adolescence; and Adolescent Aggression, characterized by low early risk that increases until Grade 9, levels out, and then declines in late adolescence. Girls were less likely than boys were to be in any trajectory besides the Low/No Aggression trajectory. Parental supervision, deviant peer association, academic orientation, impulsivity, and emotional distress at Grade 7 were all strongly associated with trajectory class membership. These associations did not differ by gender. These findings strongly suggest that the processes involved in the development of physical aggression in adolescence operate similarly in boys and girls.