The Olweus Bullying Prevention Program (BPP) is an internationally recognized school-based bullying prevention program. This project sought to evaluate pilot implementation of the program in one urban district using fidelity of implementation, bullying incident density (BID), student surveys, and serious incident reports as process and outcome measurements. Of the 13 schools that started implementation, 9 schools completed all 4 years of the project, 1 school completed 2 years, and 3 schools participated for 3 years. Results suggest a dose response relationship where schools with high fidelity to the program demonstrated reduced BID by 25%, reduced student self-reported victimization by 7%, and reduced violence-related serious incident reports by 17%. Schools with low fidelity to the program reduced BID by 35%, increased student-reported victimization by 15%, and increased serious incident reports by 31%. Facilitators of implementation were strong administrator and staff support, coordinating school rules and procedures with bullying prevention activities, and a socialized recess program. Barriers to implementation were high staff turnover, competing priorities, and misconceptions regarding the power of the program. Suggestions for future research are to continue to improve current instruments used to measure school climate and safety. Current practices in school-based violence prevention can be improved by coordinating evidence-based programs to provide a comprehensive system of care which addresses the needs of the general student population, students at risk for violence-related behaviors, and students currently or previously engaged in violence-related behaviors. (Contains 4 tables.)