This chapter explains South Korea’s approach to incorporating and implementing treaties within its domestic legal system. The chapter begins by explaining the hierarchy of the legal system in Korea with specific reference to where treaties stand in the system. Treaties duly concluded automatically become part of the domestic law under the monistic approach adopted by the Korean Constitution. More specifically, the prevailing view in Korea is that treaties ratified with the consent of the National Assembly are deemed to have the same legal status as acts or statutes. Simplified treaties without ratification proceedings, hence without legislative consent, are considered to have the status of presidential decrees or enforcement decrees under acts or statutes. Due to the increasing interaction between treaties and municipal law, recent South Korean court cases attempt to clarify other outstanding legal issues, such as the distinction between self-executing and non-self-executing treaties, and the scope of individual persons’ claims under treaties. It is expected that more challenges will be raised in the executive branch and the legislature as well as the judiciary as domestic stakeholders are increasingly affected by a myriad of treaties, in particular free trade agreements and international investment agreements. Having realized the direct impact from treaties, domestic interest groups are now keen to provide their observations and views during negotiations and to scrutinize the implementing legislation of the government after the conclusion. Thus, while the constitutional framework of treaty conclusion has remained largely the same since 1948, the domestic legal and political landscapes for treaty negotiation, conclusion, and implementation are undergoing significant changes.