International criminal law is currently subdivided into international criminal law stricto sensu — the so-called core crimes — and crimes of international concern — the so-called treaty crimes. This article suggests that the latter category can be appropriately relabelled transnational criminal law to find a doctrinal match for the criminological term transnational crime. The article argues that such a relabelling is justified because of the need to focus attention on this relatively neglected system, because of concerns about the process of criminalization of transnational conduct, legitimacy in the development of the system, doctrinal weaknesses, human rights considerations, legitimacy in the control of the system, and enforcement issues. The article argues that the distinction between international criminal law and transnational criminal law is sustainable on four grounds: the direct as opposed to indirect nature of the two systems, the application of absolute universality as opposed to more limited forms of extraterritorial jurisdiction, the protection of international interests and values as opposed to more limited transnational values and interests, and the differently constituted international societies that project these penal norms. Finally, the article argues that the term transnational criminal law is apposite because it is functional and because it points to a legal order that attenuates the distinction between national and international.