Bullying prevention in schools has arguably met with limited success in the United States. Diversity negatively impacts the success of bullying prevention programs. Furthermore, researchers do not agree upon intervention timing and appropriate grade-level to implement bullying prevention and social-emotional learning and skill-building programs. Urban schools faced with high poverty have an increased need for bullying prevention programs to alleviate bullying and aggression. The purpose of this study was to test for significant differences between urban elementary schools after a treatment group participated in a targeted bullying prevention and social skill-building program and to test for grade-level differences from fall to spring using a quantitative causal-comparative design. The sample included four urban schools in Ohio with 24 grade-levels and six time points each. The data generated were analyzed retrospectively in a causal-comparative research design. A two-way mixed ANOVA BBW was conducted on the summary totals of the number of students disciplined for bullying and aggression using six time points with three for fall or before treatment and three for spring or after treatment comparing a treatment group to a control group. Significant differences were not found between control and treatment or between grade groups (p > 0.05). Bullying and aggression started the school year and ended the school year slightly higher in the 4-6th grade group. Significant differences were found from fall to spring (F (5,16) = 7.704, p = 0.001). Overall the study findings indicate the targeted bullying prevention and social-skill building program did not result in reducing bullying and aggressive behavior in the sample population. [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/en-US/products/dissertations/individuals.shtml.]