In recent years, the British military has introduced a number of policies aimed at recruiting and sustaining demographically diverse armed forces. Central to these is a “zero-tolerance” approach to discrimination and harassment. However, by undertaking an “effective” reading of policies aimed at managing sexual orientation and gender diversity, and by drawing on qualitative research with members of the British forces, this article demonstrates how the military’s own implementation strategies facilitate discrimination against some recruits. It concludes that although the British military is understandably keen to protect its operational effectiveness, by clinging to unreflexive claims about the nature of social cohesion, and in failing to respond to societal demands for inclusion, military officials are undermining the social legitimacy of the armed forces. By extension, they are destabilizing, rather than protecting, their capabilities.