A nonconcurrent multiple baseline across 3 middle schools was used to assess the impact that teaching all students to follow the" Bullying and Harassment Prevention in Positive Behavior Support: Expect Respect" intervention had on bullying behaviors. The 3 schools were using School-Wide Positive Behavioral Interventions and Supports and as part of this effort all students in each school had been taught to discriminate "respectful" versus "nonrespectful" behavior. The "Expect Respect" intervention included, 3 1-hr lessons over a 6-month period to learn (a) how to signal "stop" when encountering nonrespectful behavior, (b) how to follow a "stopping routine" when asked to stop, (c) how to utilize the "bystander routine" when you are a witness to disrespectful behavior that does not stop even after the perpetrator has been asked to, and (d) how to recruit adult support if bullying behaviors endured. Before intervention implementation, 8 students from each school were engaged in focus groups to define the perceived need for bully prevention, and the bully prevention routines that best fit the social culture of their school. Data assessing the fidelity of intervention implementation indicate that the program was used with high fidelity and that in each of the 3 schools a reduction of verbal or physical aggression in the cafeteria was documented via direct observation. No consistent patterns were found with respect to the conditional probabilities that bystanders or recipients of bullying would use the bully prevention routines. No consistent changes were reported in student pre--post rating of school climate.