This study presents a meta-anlalytic review of 119 studies, published between 1990 and 2009, of gender differences and variables associated with overt and relational aggression during childhood and adolescence. Gender differences in overt aggression were found to be significantly higher in boys than girls, but significant gender differences in relational aggression were not found. Gender differences of only overt aggression are moderated by age and the reporter type. In general, both overt and relational aggression are more strongly related to maladjustment than adjustment. In addition to this, overt and relational aggression has both common and differential associations with relative levels of maladjustment and adjustment. The moderation of these effect sizes of both overt and relational aggression by age and the reporter type was found.