Thomas Arnold has been a controversial figure for historians of the English public schools. He has been depicted either as the great reformer of these famous institutions or as an ordinary head master who did not do better than his contemporary colleagues. This article seeks to continue the debate about the assessment of his head master-ship by using gender as a category of analysis of this early Victorian, all-male environment. It opens with a consideration of the gap that existed between the particular form of 'moral masculinity' Arnold wanted Rugby schoolboys to adopt and the different masculinities that actually emerged from the interactions of that miniature society. Bullying is particularly understood not only as an institutionalised form of rebellion but also as a gendered practice which consisted in rejecting what was considered effeminate. Finally, while it is shown that a demarcation of masculinities took place away from adult check, it is also argued that the degree of rebellion against the prescribed form of masculinity was partly dependent on the personality and methods of the 'prescriber'.