Explanations of state behavior in international relations theory and international law are frequently divided between norms and self-interest. In most discussions, these two competing explanations are portrayed as mutually exclusive. By examining one recent example of US international legal behavior-the International Criminal Court-we argue that these parallel arguments about state actions may actually converge. That is, both lines of argument may, in many instances, be complementary, and it may be hard to find sharp differences in the logic of arguments from self-interest and of arguments from norms.