The concept of ‘diversity’ has become a common feature in UK organisations over the last twenty or so years. It offers arguments about what the world is like, who people are, how they relate to one another, and how the world should be. It has been used to bring about a host of different actors, objects and practices. Yet, we know relatively little about one of the central elements of this field – diversity practitioners. They play an important role in defining what diversity means in local contexts, they are the experts of the field. Drawing on Foucault’s theories of power/knowledge and the ‘subject’, along with the notion of bricolage, the research examines the different forms of knowledge that diversity practitioners use to construct themselves as expert subjects, and in turn how they seek to construct a particular subject of others, the ‘diversity trainee’, as the subject who is the outcome of diversity training. The findings show how the subjects of the diversity practitioner and the diversity trainee are shaped by dominant societal discourses of the expert and the neoliberal subject, as well as by the history of equality work and the organisational challenges that diversity practitioners face. But they also show that diversity practitioners are actively involved in forming themselves as subjects by producing subject positions and rationalities, which construct skills, values, and knowledge. Diversity training is shown to mobilise a form of power known as ‘modern government’ in seeking to constitute the diversity trainee as a selfregulating subject, which adds complexity to previous discussions of the ethics of this form of power. Diversity practitioners are central elements of their field, so recognising the relations of power/knowledge in their practices is fundamental to considering any future development of their practices, as well as better understanding the concept of diversity itself.