This paper examines how collective masculinities, mobilized around violence, aggression and negative constructions of 'femininity', might be understood from perspectives that draw on humanist tenets of identity construction, on the one hand, and poststructural tenets, on the other. The paper presents a narrative from a study into boys' peer culture to explore the potential implications of these two different theoretical perspectives. In drawing on humanist tenets to understand boys' collective and individual behaviour, the study's data demonstrates how 'common sense' and prescriptive teacher philosophies and strategies might be seen as constraining gender justice through linear and essentially fixed accounts of masculinity. In understanding boys' collective and individual behaviours as discursively produced, the tenets of poststructural theory are presented as potentially generative for teachers in terms of enabling gender justice through an illumination of the complex, dynamic and often contestatory ways collective masculinities are spoken into existence. In making transparent spaces for transformation within a social justice framework, the tenets of feminist poststructural theory are positioned as central in enhancing boys' academic and behavioural outcomes.