This article asserts there has been a lack of attention to the impact of cultural diversity within the field of international humanitarian law. Discussions surrounding culture in international humanitarian law have nearly always avoided the central issue of cultural particularism. This has been so in relation to the debate surrounding the emblem, in general surveys of humanitarian law, and in discussions of the laws of war in distinct legal and cultural traditions. The emblems debate, in particular, signals the elusiveness of rigid universality within international humanitarian law. Five elements are suggested to explain the resistance of humanitarian law to contagion by the cultural relativism debate in human rights: the nature of human rights, the distinct normative frameworks of human rights and humanitarian law, the unified conventional basis of humanitarian law, the very broad participation in the humanitarian regime, and the unique role of the International Committee of the Red Cross. While these reasons might explain the fact that the relativism debate in human rights did not readily transfer to humanitarian law, they offer no substantive basis for immunity for humanitarian law to the challenges posed by cultural diversity. Ultimately, the article proposes a legal pluralist approach that recognizes the role of actors in the cultural process of norm-creation. Given the continued violation of the laws of war, the author suggests a need to open the door to cultural diversity in order to generate greater compliance. Without cultural legitimacy, there is a danger that humanitarian law aspires to self-defeating universalism.