WTO members can draft the Trade and Sustainable Development Agreement (TSDA) based on international and domestic trade rules and sustainable development policies. These members can build on existing frameworks to reach a consensus on establishing a sustainable development club, thereby progressively driving the reform of international trade rules and development policies. This process will eventually lead to the revision of WTO rules, effectively constitutionalising the organisation. EU trade and development policies and mega Free Trade Agreements (FTAs) offer valuable lessons for reforming international trade rules. As the most active advocate for sustainable development, the EU has incorporated numerous sustainability provisions into its trade policies. The quantity and quality of these provisions are outstanding compared to those of other national policies. Furthermore, mega FTAs represent significant efforts by the EU and other countries to integrate sustainable development policies into international trade rules. This chapter details the contents of the TSDA (i.e., the potential trade rules and policies of the sustainable development club) by highlighting the sustainability measures embedded in EU trade and development policies and mega FTAs.