This research examines how practitioners in the art museum engage with difference, particularly with the black subject, and the influence that policy, which is intended to promote access and inclusion, has on the process. How difference is imagined and addressed is explored through an investigation of the lived experience of museum professionals in both the United States and the United Kingdom. The research is an ethnographic study that utilizes a multidisciplinary theoretical framework, drawing from sociology, cultural studies, social and cultural history, art history, and museum studies, and its methodological approach includes in-depth interviews in Seattle, New York and London, and long-term participant observation in London. An examination of race, diversity and representation, an overview of historical accounts substantiating the development of support for the arts and culture, and an indication of arts policy in the US and UK provide a context from which to view the empirical data. The data makes visible how specific communities are imagined, how projects are developed for ‘targeted’ audiences, and it reveals how conventions in practice continue to perpetuate an air of exclusivity in institutions purportedly open to all. Contrasting and comparing the stated motivations and intentions of practitioners with observed practice illuminates the challenges inherent in transforming words into action. These challenges expose the mechanisms of essentialism, instrumentalism and exclusion that can be exerted in practice; analysis of the process illustrates the complexity of shifting the narrative and culture of the museum, a shift which denotes the evolution in learning and audience development from a civilizing, transmission approach towards a participatory, individual meaning-making approach. This research intends to enhance the understanding of the agency of museum practitioners, particularly during their engagement with difference and external policy mandates, whilst they are concurrently situated in the evolving material and discursive space of the art museum.