September 11 securitized the issue of terrorist financing by significantly intensifying international regulation of financial crime. Since terrorism is not restricted by state borders, terrorism financing must also be combatted transnationally. States must coordinate and standardize financial regulation at the international level, and this process takes place within international organizations. Current securitization scholarship overlooks the role of international organizations in the adoption of coordinated issue framing. I trace the process of discursive diffusion between the United Nations Security Council and the Financial Action Task Force (FATF) before and after September 11 to find that standard-setting language diffuses bidirectionally. Specifically, normative language diffuses from the generalist Security Council to the specialized FATF. Technical language diffuses from the FATF to the Security Council. I also find the formation of inextricable issue linkage between terrorism financing and money laundering. These findings have implications for the role of specialized technocratic institutions in securitization. In addition, long-term international coordination on terrorist financing may impact financial coordination on other issues, including sanctions against Russia after the 2022 invasion of Ukraine.