During most of the period from 1912 to 1936, Guangdong Province was independent from the central government. The local authorities there were facing a dilemma regarding opium, as others were elsewhere in China. On the one hand, opium was considered the symbol of China’s weakness, and its suppression was a top priority; on the other hand, opium taxes represented an indispensable source of fiscal income. Some Guangdong power holders were truly committed to a suppression agenda, especially from 1913 to 1924. During this period, with the exception of a brief interlude from 1915 to 1916, opium laws were prohibition laws. Even if these laws were not always enforced with full vigor, the drug remained illegal in Guangdong. After 1924, opium was legalized, and the authorities openly ruled an opium monopoly. They came out with increasingly comprehensive regulations, which proved successful in increasing opium revenues. Yet, as this article makes clear, there was nothing like direct government control: traditional tax-farming arrangements with local opium merchants (though under stricter supervision) remained the backbone of the monopoly. The article also pays attention to the influence of the Six-Year Plan (1935–1940) launched by the Nanking government. As a credible set of suppression laws, it appealed to the Guangdong progressive elites who were hostile to opium. They urged the local autocrat Chen Jitang to take similar action. Chen made attempts to launch his own plans for suppressing opium, but they were unconvincing and nothing concrete came out of them. This article suggests that, in order to obtain a better understanding of how easily Chen Jitang was driven out of power in the summer of 1936, it is necessary to take into account the significant contribution of the Six-Year Plan in undermining his legitimacy.