Underage drinking is a major health concern. Alcohol is the most commonly used substance among adolescents. According to Monitoring the Future project, approximately 39% of eighth-grade students and 72% of adolescents by the end of high school report consuming more than a few sips of alcohol. Further, 55% of students in Grade 12 and 19% of those in Grade 8 report having been drunk at least once in their life. Although most underage drinkers will not develop a dependency on alcohol, the consequences of alcohol consumption are significant. Alcohol use is a common factor in the leading cause of morbidity and mortality for this age group, that is, accidents. This entry focuses on at-risk factors and interventions for underage drinking.