The concept of masculinity has been critiqued either as an ideological effect of patriarchy or as a play of discourse. This occurs at a time when there is renewed interest in biologically reductive theories of gender, and in the context (in the UK) of public disquiet about boys' academic performance. This paper argues that while masculinity cannot be regarded as a foundational subject, the reality of the category 'masculinity' in the daily lives of students and teachers means that we have to take account of how it structures both the social and pedagogic life of the classroom. The paper demonstrates how an imagined sense of masculinity--the masculine social imaginary--appears as a reality in the boys' narratives of self. The paper also argues that while this masculine social imaginary provides the semantic logic of gender, it is in the moment-to-moment interactions that boys have to assert and seek recognition of themselves as male. 'Masculinity' continues to be a useful sociological concept.