This article examines the effects of ASEAN treaties in the Vietnamese legal system. It demonstrates that, in addition to modifying domestic laws, ASEAN treaties, especially those adopted to promote regional economic integration, could also influence the domestic legal order by changing current administrative procedures, introducing new administrative mechanisms, and improving the overall operation of government agencies. This process may not be immediately discernible from an examination of changes in domestic laws; however, once the inquiry is broadened to include details of treaty implementation via administrative procedures, the impact of treaties comes into sharper focus. This impact of treaties on administrative procedures, while relatively easy to overlook, may represent the most important portion of the impact of ASEAN treaties on Vietnam’s legal order. More broadly, it also illuminates a larger point about the indirect, more subtle, and less visible influence that international law may exert on national law and procedures.