The latest national survey of high school seniors by the University of Michigan's Institute for Social Research shows that nearly two-thirds of American teenagers have used drugs at least once before they finish high school. About 40 percent have used drugs other than marijuana, and 9 of 10 seniors reported having experienced alcohol. One in five seniors is a daily cigarette smoker, and marijuana is the most widely used illicit drug. A 1982 survey by the National Institute on Drug Abuse (NIDA) estimates that 8.1 million 12- to 15-year-olds have experienced alcohol and that about 6 million have smoked cigarettes at least once. A 1985 NIDA report indicates that 93 percent of high school seniors have used alcohol. The rate of occasional heavy drinking or party drinking rose from 37 percent in 1975 to 41 percent in 1979 and remained at this level through 1983. In 1984, the rate of party drinking fell to 39 percent. Teenagers say drug abuse is the biggest problem they face, followed by alcohol abuse and unemployment. By definition, drug and alcohol use by children is a criminal offense. The right of school officials to enforce the law in schools and combat drug abuse and trafficking on campuses has been addressed in major court decisions on student searches. Many drug prevention programs, designed to address underlying problems that may cause drug abuse, emphasize self-esteem and are usually aimed at adolescents between 11 and 15 years of age. Joint efforts between school administrators and law enforcement agencies are essential to decrease drug abuse by students.