We investigated implementation fidelity of programmatic activities of the Olweus Bullying Prevention Program (OBPP) among 2,022 teachers, 88.5% female, from 88 elementary schools located in Pennsylvania. Results indicated that the majority of respondents had attended the school kick-off event, posted the rules in the classroom, and explained the rules to students. Receiving booster sessions and activities involving parental involvement were the least likely elements to have been performed. Logistic regression analyses revealed that teachers with confidence in their ability to implement the OBPP had completed all of the OBPP programmatic activities. Similarly, multiple regression analysis results revealed that teachers with self-efficacy to implement the OBPP implemented more components than respondents without self-efficacy. In addition, teachers with more OBPP experience were more likely to have completed individual-level activities. Our findings reveal that certain OBPP components are easier to perform than others and that implementer characteristics matter.