The author, who was a new young officer at the time of his undercover work, posed as a 12th-grade student in the school, whose administrators had requested an undercover officer to investigate drug use and drug dealing by students. The undercover work produced the arrest of two seniors for selling 10 ounces of cocaine to the undercover officer. The author notes that one of the most disturbing aspects of his work was learning that many of the involved students' parents and teachers had no idea of the drug involvement of their child or student. Parents and teachers are advised to educate themselves about drugs and the signs of drug use. This article provides information on the nature, effects, use signs, and sale of the following common drugs among high school students: marijuana, cocaine and crack cocaine, and LSD and other drugs ("ecstasy," heroin, and PCP). A separate section of this article addresses the signs of drug use. The author concludes by advising that the best way to reduce drug activity among youth is for parents, teachers, school staff, police, and students to work together in removing drugs from schools.