This chapter examines the creation of the 1961 UN Single Convention on Narcotic Drugs. It was also a period when transatlantic relations reached a new low in drug diplomacy. Minor cooperation in the aftermath of the 1953 Opium Conference gave way to divisions leading to an eventual rupture over the Single Convention, particularly between Britain and the US. This breakdown was ultimately was the result of failures of US leadership as well as deep divisions over policy and economic interests. The US found itself increasingly alone in negotiations. State Department leadership sought a more conciliatory approach towards producers like Iran and Afghanistan. Nevertheless, with Anslinger increasingly absent and with a lack of institutional knowledge within the State Department US delegations struggled to develop a US grand strategy. Britain, continuing to carve out a role of quiet, consensual and self-interested drug diplomacy, found the new environment conducive and became increasingly assertive. London pragmatically worked with shifting coalitions, while building a moderate bloc of manufacturing states in Europe to help protect British domestic interests via the Single Convention. The result was a consensus-based treaty and one largely rejected by the US, which tried and failed to torpedo the treaty.