The use of cocaine in the United States began during the mid-1880s, reached a peak between 1900 and 1915, and then went into a period of sustained decline. This study examines several explanations for cocaine's decline, and concludes that the start of legal prohibition was only partly responsible. Legal controls virtually eliminated the licit supply of cocaine, and increased the costs of obtaining illicit supplies. These trends, however, had begun much earlier as a result of regulation and informal controls. Moreover, the “successs” of legal prohibition depended upon a number of unique historical circumstances, including the ready supply of cheap heroin for domestic drug markets. The conclusion of the first cocaine era was neither an inevitable end to a “cycle” of drug use, nor the outcome of a well-planned set of drug policies, but the product of a combination of national and international trends.