In discussions of conflict, war and political violence, dead bodies count. Although the politics and practices associated with the collection of violent-death data are seldom subject to critical examination, they are crucial to how scholars and practitioners think about how and why conflict and violence erupt. Knowledge about conflict deaths – the 'who, what, where, when, why and how' – is a form of expertise, created, disseminated and used by different agents. This article highlights the ways in which body counts are deployed as social facts and forms of knowledge that are used to shape and influence policies and practices associated with armed conflict. It traces the way in which conflict-death data emerged, and then examines critically some of the practices and assumptions of data collection to shed light on how claims to expertise are enacted and on how the public arena connects (or not) with scholarly conflict expertise.