This discussion paper has been prepared for the workshop on "Implementation and Compliance in International Law: Implications for Pandemic Rulemaking," which took place on July 6, 2023, at the Geneva Graduate Institute. The workshop aimed to provide an opportunity for members of Geneva-based permanent missions and government officials from capitals to delve into theories and practices of implementation and compliance across different international legal regimes. Currently, Member States of the World Health Organization (WHO) are actively negotiating an international agreement on pandemic prevention, preparedness, and response (WHO CA+) and amendments to the International Health Regulations (IHR). While discussions are still at an early stage, the workshop at the Geneva Graduate Institute offered an opportunity to initiate reflections on the wide range of implementation and compliance mechanisms available under international law and their relevance in light of the ongoing negotiations. This paper begins by introducing theories of compliance in international law. It then presents examples of institutions and practices related to implementation and compliance within three distinct regimes: human rights, anti-corruption, and multilateral environmental agreements. Finally, it provides a synthesis of the main elements of implementation and compliance present across various international legal frameworks and compares them with specific provisions of the Bureau's Text of WHO CA+ and proposed amendments to the IHR.