Despite a nationwide trend to increase security measures in schools, their effectiveness in reducing or preventing student misbehavior remains largely unexamined. In addition, there is concern that increased security may have unintended negative side effects and is applied inequitably across students of disparate racial/ethnic backgrounds. The purpose of this study was to explore student differences between high- and low-security schools and to understand the relationship of security to student misbehavior. Data from 10,577 Grade 10 students from 504 public schools from the Education Longitudinal Study were examined. Numerous differences in students served by high- and low-security schools were noted; high-security schools were more likely to serve African American students. Security was negatively associated with student self-reported misbehavior but was unrelated to teacher ratings. Security interacted with race/ethnicity such that African American students were rated as having higher levels of disruptive and attendance-related misbehavior by teachers in schools with higher levels of security.