High school students who taught the Protecting You/Protecting Me (PY/PM) curriculum to elementary students were found to have made modest gains, relative to high school students in the matched comparison group. PY/PM students improved their knowledge of the effects of alcohol on the developing brain, increased their perceptions of the risk associated with high levels of alcohol use, and decreased binge drinking. The findings suggest that students who taught PY/PM learned that high levels of alcohol were damaging to the brain and subsequently reduced the amount of alcohol they consumed. In addition, PY/PM students improved in their teaching skills. Adolescents continue to use alcohol in alarming numbers, despite the consequences of underage alcohol use. Several programs have demonstrated success in reducing or preventing use of alcohol by youth. Developed by Mothers Against Drug Driving (MADD), PY/PM constitutes one such program. The program uses trained high school peer helpers to deliver an alcohol prevention and vehicle safety curriculum to students in elementary grades. The goal of the classroom-based program is to prevent the injury and death of children and youth caused by underage alcohol use and riding in vehicles with impaired drivers. This study evaluated the impact of the PY/PM program on high school students. Tables, references