This is a book review of Yuji Iwasawa, Domestic Application of International Law: Focusing on Direct Applicability, Brill | Nijhoff, 2022. Iwasawa compellingly explains why the question of direct applicability is important and why this matter deserves more attention. He simultaneously gives a comprehensive account of the area while making a forceful argument on how to theoretically and practically approach questions where there is still disagreement. In addition, and acknowledging that the question of domestic application of international law is vast, Iwasawa’s book provides a highly suitable framework for future research.