Self-regulation has been shown to play a protective role against youth substance abuse, but less is known about its influence on bullying behavior. In the present study, we examined several forms of bullying (physical, social, cyber, and all forms combined) and roles (bullies, victims, and bully-victims). Students (N = 1977, ages 11 to 13) from 27 middle schools throughout the United States (US) completed an online self-reported assessment of bullying and its hypothesized etiologic determinants. Across the outcomes, analyses revealed that social bullying was most prevalent, followed by physical bullying and cyberbullying. For bullying roles, almost two-thirds of students reported bullying victimization, nearly one-quarter reported bullying perpetration, and one in five students reported both. Of those reporting perpetration, 9 of 10 reported being victimized. Multivariate logistic regression models were used to examine the associations between self-regulation, bystander intervention skills, and bullying. For all forms of bullying combined, self-regulation was protective against bullying perpetration (OR 0.51, 95% CI: 0.42, 0.63) and perpetration/victimization (OR 0.55, 95% CI: 0.44, 0.68), while bystander intervention skills were not protective. Similar patterns emerged for physical, social, and cyberbullying. Collectively, these findings indicate that building self-regulation skills may be a critical component of interventions aimed at preventing bullying among school-aged youth.