Individual sections focus on the enforcement activities of the Drug Enforcement Administration (DEA) and other Federal, State, and local agencies; on drug abuse indicators; and on DEA training activities. Narrative texts accompany the data tables. In summary, heroin arrests nationwide stabilized during the first half of calendar year 1980 after decreases in 1978 and 1979, while DEA/foreign cooperative arrests increased. Both Federal and foreign cooperative heroin removals increased. Total domestic and foreign cocaine arrests and removals rose substantially, and marihuana arrest and removal statistics (with the exception of foreign cooperative figures) remained high. Increased enforcement activity was reflected in increased dangerous-drug arrests and removals as well. A steady increase in heroine, cocaine, and stimulant abuse was recorded. The national purity of heroin increased slightly in 1979 for the first time since 1976, due to a resurgence of Southwest Asian heroin. Hallucinogen indicators for the first half of 1980 reflected either a leveling off or a decrease from the surge in abuse which began 3 years ago, and depressant abuse stabilized. DEA provided major training efforts to foreign, State, and local governments. Within the United States, these efforts are designed to better coordinate the activities of foreign and State governments and to inform officials of the latest drug law enforcement techniques.