This brief discusses the signs and symptoms of alcohol and drug use and provides recommendations to assess substance use among youth in your program. It is not uncommon for adolescents to experiment with different substances such as alcohol or cigarettes, but this can lead to heavy and continued use, which is dangerous and may put their health at risk. Additionally, individuals who drink and smoke are more likely to participate in other risky behaviors, including using other drugs or driving after drinking. Adolescents may turn to substance use when they are under stress at home or at school, or when their friends are smoking or drinking. (Contains 10 endnotes.)