Background: National estimates of middle school bullying approximate 40%, making it the leading form of school violence. Meta-analysis of conventional anti-bullying efforts have shown mixed results, averaging small reductions in bullying behavior. Social-Emotional Learning and PositiveYouth Development provide a theory-driven alternative for approaching bullying and victimization by strengthening social competencies that reduce related youth risk behaviors. Methods: A sample of 7th grade students ("N" = 323) participated in "Take the Lead" (TTL); a 16-session curriculum designed to build social competencies of all participants. Data were coded and collected using a pretest/posttest time-lag control group cohort study design. Participants self-reported bully and victim behaviors using the Peer Relations Questionnaire. Extracted data were assessed for changes in bullying and victim behaviors, from pretest to posttest, between groups and sexes. Results: Participants in TTL reported significant reductions in bullying (p less than 0.001), and victimization (p less than 0.001), from pretest to posttest, and compared to controls (p less than 0.001) Findings remained consistent between sexes (p less than 0.001). Control groups experienced increases in bully and victim behaviors during the same time period, which were significantly reduced following participation in TTL (p less than 0.001). Conclusion: Identifying intervention alternatives to address bullying behaviors must remain a research priority. This study supports the application of theory-driven SEL and PYD constructs within a curriculum designed to improve social competencies of all students. (Contains 4 tables.)