Bullying is a health problem related to depression, eating disorders, homicide, and suicide. Approaching bullying as a health issue in need of effective treatment may prevent much unnecessary suffering. The Olweus Bullying Prevention Program was developed in Norway. The purpose of our project was to determine whether the Olweus Bullying Prevention Program worked in inner city schools in the United States. To evaluate the Olweus Bullying Prevention Program, levels of bullying were examined before, during, and after the program. Each school was scored on how well it adhered to the original program, a concept known as fidelity of implementation. Student surveys, violence-related serious incident reports, and observations of students in lunches and recess were collected in 36 schools over 9 years. Student surveys and serious incident reports showed a dose-response relationship where violence-related behaviors decreased in high-fidelity schools, those that implemented 75% or more of the program components, and increased in low-fidelity schools. The project offers insights into how to establish successful community collaborations, the benefits and obstacles to community-based research, and limitations of different types of data. [This content is provided in the format of an e-book.]