This article looks at the development of the concept of crimes against humanity at the International Criminal Tribunal for Rwanda (ICTR). It contends that the ICTR’s interpretation of crimes against humanity is generally seen by international lawyers as a commendable, but unsurprising, step in the historical development of this category. In much the same way, the ICTR’s historical account is considered to be a standard attempt by a war crimes court to relate a liberal history of crimes against humanity in a way that upholds civilized values. Yet, although the historical and legal work of the ICTR appear unexceptional, this article will argue that they do demonstrate a particular conceptual approach towards warfare, history, humanity, and the nature of international law. Moreover, this is a conceptual approach that is quite different to that taken by the International Military Tribunal at Nuremberg. The article suggests that these differences, and the invisibility of the change, are due to the ICTR’s reliance on familiar narrative tropes. These narratives were established through poststructuralist theory but could be expressed in a variety of more or (often) less theoretical forms. By exploring the influence of these narratives on the Tribunal, it is possible to examine some of the ways in which conceptual change is facilitated and knowledge is created in international law. In particular, it shows how theories that are often considered marginal to international law have had a significant impact on some of the central provisions of international humanitarian law.