This article explores some of the issues that have given rise to the perception of an increase in aggressive behaviour by females. It asserts that merely comparing girls' behaviour with that of boys, especially the claim that "girls are behaving like boys", trivialises the very real issues associated with females and aggression. This paper will refer to recent research into girls and aggression and will also propose that the prevailing discourse of gender dualism contributes to the lack of early identification and support services for girls at risk of severe aggression at adolescence.