This article builds from original fieldwork to show what lies behind China’s remarkably successful use of international trade law to take on the United States and Europe. The World Trade Organization (WTO) is unique in China’s international relations as it is the only forum where China, with its anti-legalist traditions, has resolved its disputes through law and the use of third party dispute settlement. After China acceded to the WTO in 2001, it invested massively in building trade law capacity to transform itself and defend itself externally. Through these investments and its increased market power, China became a serious rival to the U.S. and Europe in the development and enforcement of international trade law. This article provides the most complete account of this important development, which has had significant political impacts within the United States and Europe. The article first explains China’s significant trade law capacity-building efforts in government, academia, law firms, and business. It then assesses the broader implications for the international trade legal order. It shows that global economic order itself is at stake, affecting citizens around the globe. The article builds from research involving over a decade of original fieldwork in China, Washington D.C., Brussels, and Geneva.