This article analyzes China’s attempts to participate in and use the negotiations about reforming the international opium control system in the interwar period. China had a contentious relationship with the international opium control system from its creation in the International Opium Convention of 1912 through the League of Nations opium control system of the 1920s and 1930s. The Chinese government wanted to gain acceptance for China as a modern state no longer in need of tutelage from the international community. They also wanted to portray the Chinese people as a modern race as a way of undermining colonial opium monopolies, which made a disproportionate amount of their profits from sales to Overseas Chinese. While they were not fully successful in either of these efforts, China did manage to win some support, drawing the United States into closer agreement with China’s positions. Engagement with the international system also had a considerable impact on China’s domestic opium politics and its broader diplomatic relationship with the major powers.