An overview emphasizes that drug abuse has increased so rapidly over the past two decades that it now threatens all countries and all parts of society. Marijuana is the most commonly abused drug, but the continued spread of heroin use and the marked increase in cocaine abuse is a source of major concern. Amphetamines, benzodiazepines, and barbiturates are also widely used. The use of multiple drugs, often including alcohol and tobacco, increases the adverse effects on the drug abuser. Intravenous drug users are also at risk of AIDS. The illicit production and manufacture of drugs are occurring in a growing number of countries in many regions of the world. Increasing numbers of countries are making drug control a higher priority. The International Conference on Drug Abuse and Illicit Trafficking permitted a global reexamination of the issues involved. Most countries are actively cooperating with each other, and many governments are strengthening their drug law enforcement capabilities. Descriptions of efforts in specific countries