Adolescents who are addicted to drugs present unique assessment and diagnostic problems. The primary drugs used by adolescents are alcohol, marijuana, and cocaine, respectively. The adolescent who uses drugs in a regular and frequent manner is affected more rapidly than is the adult who uses in the same way and for the same length of time. The social and emotional skills usually acquired during this period of rapid growth often are not learned when the adolescent is abusing drugs, and this results in psychosocial stunting of development. Drugs and alcohol have been implicated in teenage traffic accidents, school drop out rates, promiscuity, crime, and suicide. Assessing adolescent drug use and potential addiction is not difficult once good history and examination techniques are acquired. This article presents techniques for assessing and identifying addicted adolescents.