Background: Weight misperception has been documented among children although the impact on health risk behaviors is less understood, particularly among middle school students. The goals of this study were to describe sociodemographic differences in actual and perceived weight, correspondence between actual and perceived weight, and weight-related health risk behaviors, as well as to examine weight misperception and interactions with sociodemographic variables in explaining weight-related health risk behaviors. Methods: Participants were recruited at 11 public school districts participating in the Tennessee Coordinated School Health (CSH) pilot program. A total of 10,273 middle school students completed the Centers for Disease Control and Prevention's Youth Risk Behavior Survey administered by teachers in the school setting. Results: Findings revealed sociodemographic differences in actual and perceived weight as well as weight misperception. Although overestimating one's weight was significantly related to greater likelihood of weight-related health risk behaviors, significant interactions showed this relationship to be especially pronounced in females. Additional distinctions based on sociodemographic variables are indicated. Conclusions: Results highlight the importance of screening for health risk behaviors including weight misperception among middle school students. The CSH program offers an opportunity to understand health risk behaviors among students while also informing and evaluating methods for intervention.