This ethnographic research interrogates the relationship between sexuality, gender and homophobia and how they impact on 16- to 18-year-old boys in a coeducational sixth form in the south of England. Framing our research with inclusive masculinity theory, we find that, unlike the elevated rates of homophobia typically described in academic literature, the boys at ‘Standard High’ espouse pro-gay attitudes and eliminate homophobic language. This inclusivity simultaneously permits an expansion of heteromasculine boundaries, so that boys are able to express physical tactility and emotional intimacy without being homosexualized by their behaviours. However, we add to inclusive masculinity theory by showing the ways in which boys continue to privilege and regulate heterosexuality in the absence of homophobia: we find that heterosexual boundary maintenance continues, heterosexual identities are further consolidated, and the presumption of heterosexuality remains. Accordingly, we argue that even in inclusive cultures, it is necessary to examine for the processes of heteronormativity.