Schools take different approaches to creating and fostering a healthy and safe environment for youth. Varied approaches include setting limits for acceptable behavior, defining the consequences for breaking school rules, and the provision of services to address problem behaviors. One important issue that schools have to address is substance use among students, particularly during adolescence, when substance use is often initiated. Although not all youth who experiment with drugs and alcohol in adolescence continue to use substances or develop substance use dependencies as adults, adolescent substance use is highly predictive of young adult substance use. Using data from the Longitudinal Study of Adolescent Health (Add Health), this brief seeks to illuminate the relationship between school substance-use policies, school connectedness, and young adult drug and alcohol use.