In the United States, nearly two-thirds of all deaths among young people 10-14 years of age result from only five causes: motor-vehicle crashes (22.1%), other unintentional injuries (16.7%), cancer (12.9%), suicide (6.8%), and homicide (4.7%). Leading causes of illness and death in all age groups in the United States are related to the following: behaviors that contribute to unintentional injuries and violence; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and STDs, including human immunodeficiency virus (HIV) infection; unhealthy dietary behaviors; and physical inactivity--plus overweight. These behaviors are frequently interrelated and are often established during youth and extend into adulthood. To monitor priority health-risk behaviors among adolescents and young adults in each of these six categories, the Centers for Disease Control and Prevention (CDC) developed the Youth Risk Behavior Surveillance System (YRBSS). The YRBSS includes national, state, and local school-based surveys of high school students in grades 9-12. In addition, some states and cities conduct a school-based Youth Risk Behavior Survey (YRBS) among middle school students. In 2003, eight states and eight cities conducted a middle school YRBS. This report summarizes results from the seven state and six local middle school surveys with weighted data in 2003. Six weighted state surveys and six weighted local surveys were conducted during spring 2003. One weighted state survey was conducted during fall 2003. Data from the one state and one local school-based survey with unweighted data are not included in this report. (Contains 248 tables.)