Preventing bullying requires a comprehensive approach that includes a focus on school climate. We review the climate features shown to reduce bullying, then illustrate how School-wide Positive Behavioral Interventions and Supports (SWPBIS) applies these principles in practice. SWPBIS, grounded in multiple theories--behaviorism, social learning theory, prevention science, and systems change--is designed to build a positive school climate by defining and consistently reinforcing positive behavioral norms. SWPBIS focuses on teaching and acknowledging positive behavior and addressing environmental conditions that exacerbate problem behavior. This positive approach changes behavior without the negative interactions associated with punitive discipline while establishing school climates that promote protective factors and mitigate risk factors. Schools implementing SWPBIS have reported less bullying and student victimization, fewer problem behaviors, and increased feelings of safety.