Using a post-structural framework, the paper analyses the dynamics of the process by which little boys adopt a definition of masculinity as avoiding whatever is done by girls. It is argued that this is a response to the fact that the 'fighting boys' who resist the school's demands have appropriated the role of hero in the warrior narratives of little boys' fantasy games, casting the 'good boys' who conform to the requirements of the school as despised 'wimps' and 'sissies'. This leads the 'good boys' to adopt an alternative definition of masculinity as 'not female', and in many cases leads also to the scorn and rejection being redirected to girls as a group. It is suggested that teachers should intervene in this cycle by explicitly discussing the character of the hero in these warrior narratives and showing that it ought not to be equated with the classroom and playground behaviour of the 'fighting boys'.