Book excerpt: Tobacco use by adolescents and young adults poses serious concerns. Nearly all adults who have ever smoked daily first tried a cigarette before 26 years of age. Current cigarette use among adults is highest among persons aged 21 to 25 years. The parts of the brain most responsible for cognitive and psychosocial maturity continue to develop and change through young adulthood, and adolescent brains are uniquely vulnerable to the effects of nicotine. At the request of the U.S. Food and Drug Administration, Public Health Implications of Raising the Minimum Age of Legal Access to Tobacco Products considers the likely public health impact of raising the minimum age for purchasing tobacco products. The report reviews the existing literature on tobacco use patterns, developmental biology and psychology, health effects of tobacco use, and the current landscape regarding youth access laws, including minimum age laws and their enforcement. Based on this literature, the report makes conclusions about the likely effect of raising the minimum age to 19, 21, and 25 years on tobacco use initiation. The report also quantifies the accompanying public health outcomes based on findings from two tobacco use simulation models. According to the report, raising the minimum age of legal access to tobacco products, particularly to ages 21 and 25, will lead to substantial reductions in tobacco use, improve the health of Americans across the lifespan, and save lives. Public Health Implications of Raising the Minimum Age of Legal Access to Tobacco Products will be a valuable reference for federal policy makers and state and local health departments and legislators.