The evidence is clear and consistent that although drug use by youth (9th-12th grades) is still well below the peak levels of the late 1970's, youth drug use increased steadily in the 1990's. Studies of drivers injured in crashes or cited for traffic violations showed that many had used drugs. Self-reported information confirmed that teens use marijuana in driving situations. It is illegal in all States to drive a motor vehicle under the influence of either alcohol, drugs other than alcohol, or a combination of alcohol and other drugs. This report presents a table of State laws related to drug use and driving. Since drugged drivers are more difficult to detect, arrest, and prosecute than alcohol-impaired drivers, the Drug Evaluation and Classification program was developed to train police officers to recognize the signs and symptoms of drug use and to classify the drug that is causing a person's impairment. Drug training is also available for prosecutors and judges. This report has a section on drug-testing experiences, methods of drug testing, drug-testing procedures, and drug-testing costs and time requirements. This report recommends stronger laws, more consistency in enforcement, prosecution, adjudication, prevention, education, publicity, drug testing, and treatment for drug use when appropriate. Such a comprehensive, multi-pronged strategy has reduced driving under the influence of alcohol, especially for youth, and it could do the same for other drugs. 1 table