Teachers are key players in efforts to address school bullying and peer victimization. Recent studies found that teachers' responses to peer victimization can vary based on their beliefs and attitudes. We examined relations among teacher self-efficacy, teachers' intentions to use recommended antibullying practices, and peer victimization as rated by teachers and students. In Study 1 (N = 79), we examined the internal structure, reliability, and initial validity of the Teacher Efficacy for Antibullying Scale (TEAS), a new measure of teachers' self-efficacy regarding school bullying and peer victimization. In Study 2, we used data from elementary school teachers (N = 34) and their students (N = 654) to test whether the interaction between teacher self-efficacy and intentions to use recommended antibullying practices predicted children's peer victimization. We also tested whether the relation between teacher self-efficacy and children's peer victimization was curvilinear. Using hierarchical linear modeling (HLM), we found support for a curvilinear relation between teacher self-efficacy and children's peer victimization that was moderated by teachers' intentions to use antibullying practices; except in classrooms where teachers held very strong intentions to use best practices, children's peer victimization was greater in classrooms where teachers reported either very low or very high self-efficacy relative to classrooms where teachers had more moderate levels of self-efficacy. Discussed are the research and practice implications of these findings for teacher-based antibullying training and intervention.