Abstract
According to official figures, most of the trouble in schools is caused by boys. This is because boys are more openly disruptive and overtly aggressive. However, recent research has uncovered forms of aggression more common among girls. This paper reports on a study in South Australian schools which explores gender and developmental differences in aggression. A peer estimation scale was administered to students in years 2, 6, 9 and 11 in two high schools and four primary schools. Boys were found to be more physically and verbally aggressive than girls but girls used more indirect forms of aggression during the high school years. The gender differences in aggression are linked to gender differences in friendship patterns. Implications for schools are briefly discussed.