Results found that since 1991, the prevalence of many health-risk behaviors among high school students nationwide has decreased. However, many high school students continue to engage in behaviors that place them at risk for the leading causes of mortality and morbidity. The prevalence of most risk behaviors does not vary substantially among cities and States. The results include findings on behaviors that contribute to unintentional injury, such as seat belt use, helmet use, alcohol related motor vehicle activity, and behaviors that contribute to violence, such as carrying weapons, fighting, dating violence, and sexual assault. Alcohol, tobacco, drug use, and lifestyle related issues are also covered. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults, including behaviors that contribute to unintentional injuries and violence; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV) infection; unhealthy dietary behaviors; and physical inactivity. YRBSS includes a national school-based survey conducted by the CDC, and State and local school-based surveys conducted by State and local education and health agencies. Data were collected from the national survey, 39 State surveys, and 22 local surveys conducted among students in grades 9–12 during 2007. For the 2007 national YRBS, 14,103 questionnaires were completed in 157 schools. Tables, references