The article focuses mainly on the politics of that process, through its transnational context (in Peru's close yet ambivalent ties with the United States in the history of cocaine) and its context in the regional political economy of cocaine. The key fact is that Peru lagged over 4 decades in criminalizing cocaine, a long pause during which the heroic, nationalist or modernizing repute of Peruvian cocaine, produced in the late 19th century, lived on in new, old, and revealing forms. The chapter traces the roots of Peru's legal cocaine industry during the years 1880-1930 and its complex relations with the United States and other global networks. It recounts the era of the 1930's, when Peru came closest to actually contesting the global tide of anti-cocainism. Finally, it examines the decade 1940-1950 and the global and local factors that had to change for Peru to make cocaine a pariah and illicit drug at its source of supply. The chapter considers whether Peru was a resistant or merely a reluctant partner in that shift and whether cocaine prohibitions were a United States export or a nationally constructed regime. Primary sources, notes