The Convention on Psychotropic Substances of 1971 is a United Nations treaty designed to control psychoactive drugs such as amphetamine-type stimulants, barbiturates, benzodiazepines, and psychedelics signed in Vienna, Austria on 21 February 1971. The Single Convention on Narcotic Drugs of 1961 did not ban the many newly discovered psychotropics, since its scope was limited to drugs with cannabis, coca, and opium-like effects.

During the 1960s such drugs became widely available, and government authorities opposed this for numerous reasons, arguing that along with negative health effects, drug use led to lowered moral standards. The Convention, which contains import and export restrictions and other rules aimed at limiting drug use to scientific and medical purposes, came into force on 16 August 1976. As of 2013, 183 member states are Parties to the treaty. Many laws have been passed to implement the Convention, including the U.S. Psychotropic Substances Act, the UK Misuse of Drugs Act 1971, and the Canadian Controlled Drugs and Substances Act. Adolf Lande, under the direction of the United Nations Office of Legal Affairs, prepared the Commentary on the Convention on Psychotropic Substances. The Commentary, published in 1976, is an invaluable aid to interpreting the treaty and constitutes a key part of its legislative history.

Provisions to end the international trafficking of drugs covered by this Convention are contained in the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances. This treaty, signed in 1988, regulates precursor chemicals to drugs controlled by the Single Convention and the Convention on Psychotropic Substances. It also strengthens provisions against money laundering and other drug-related crimes.