Boxing gyms in the Netherlands, which were traditionally bastions of ‘white’ men, have become more and more diverse. Since boxers with different ethnic backgrounds and women have joined boxing clubs, trainers need to manage this emerging diversity in their gyms. This empirical study of a gym in the Netherlands, where full participation of women is the norm, attempts to gain insights about practices of and experiences in the regulation of social inclusion and exclusion. We explore points of connection between Foucault’s conceptualization of regulation and disciplinary techniques and the regulatory and embodied practices of boxing. In this case study, observations and interviews were conducted to explore how trainers address diversity of members in training sessions and at matches. The results show how the participation of male and female boxers with different ethnic backgrounds was normalized by trainers. The gym, with a traditional hierarchical and patriarchal culture, enabled trainers to use disciplinary techniques to normalize their construction of what is normal in the gym. These trainers are not all-powerful, however, and had to negotiate their construction of boxers in interaction with others. The use of disciplinary techniques produced both uniformity and differentiation and, through an ongoing process of negotiation, they defined who would be included or excluded.