Alcohol use health consequences are considerable; prevention efforts are needed, particularly for adolescents and college students. The national minimum legal drinking age of 21 years is a primary alcohol-control policy in the United States. An advocacy group supported by some college presidents seeks public debate on the minimum legal drinking age and proposes reducing it to 18 years. We reviewed recent trends in drinking and related consequences, evidence on effectiveness of the minimum legal drinking age of 21 years, research on drinking among college students related to the minimum legal drinking age, and the case to lower the minimum legal drinking age. Evidence supporting the minimum legal drinking age of 21 years is strong and growing. A wide range of empirically supported interventions is available to reduce underage drinking. Public health professionals can play a role in advocating these interventions.