This study examined the effect of an anti-bullying program, Cyberbullying: A Prevention Curriculum for Grades 6-12 (Limber, Kowalski & Agatston, 2008). A quasi-experimental post-test design was used to investigate (a) whether or not participation in the program was related to the frequency of aggressive on-line experiences for victims and/or offenders, or cyberbullying, and (b) whether the mode of program delivery (student-led versus teacher-led) had an effect on frequency of aggressive on-line experiences for victims and/or offenders, or cyberbullying. The student led experimental group, as well as the teacher led experimental group, received Cyberbullying: A Prevention Curriculum, while a control group completed team building activities not related to the topic of bullying. The sample population consisted of 154 students in middle school from a middle to upper middle class school district in the Northeast. At the conclusion of the study, all participants were administered the Cyberbullying and Online Aggression Survey Instrument (Hinduja & Patchin, 2007) to measure their experiences with on-line aggressive victim and offender experiences. Data were analyzed using four chi-square tests of independence analyses. Results showed that, overall, participation in the program was associated with fewer than expected on-line victim and/or offender experiences when an anti-cyberbullying program was implemented. However, when expected and observed frequencies for student-led and teacher-led groups were compared, participation in the program led by a student leader was only associated with fewer than expected on-line victim and/or offender experiences on the offending subscale. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]