Background: Teachers play a critical role in protecting students from harm in schools, but little is known about their attitudes toward addressing problems like bullying. Previous studies have rarely used theoretical frameworks, making it difficult to advance this area of research. Using the Extended Parallel Process Model (EPPM), we examined the association between teachers' perceived threat and perceived efficacy and their likelihood of intervening in bullying situations. We also explored whether the school level at which teachers taught (elementary vs secondary), and their years of experience of working at the school moderated these associations. Methods: Data come from 1062 teachers who completed an anonymous Web-based survey regarding their attitudes and responses to bullying. Structural equation modeling and multiple group analyses were used to test the hypothesized relationships and for effect modification by teacher characteristics. Results: Perceived threat and efficacy were associated with teachers' likelihood of intervening in bullying situations but varied based on teachers' years of experience at their school. For less experienced teachers, perceived efficacy, but not perceived threat, was strongly associated with likelihood of intervening. For more experienced teachers, both perceived threat and perceived efficacy were significantly associated. Finally, the associations did not differ by the school level. Conclusion: This is one of few studies examining possible predictors of teachers' likelihood of intervening in bullying situations. EPPM may inform the development of bullying interventions aiming to increase the likelihood that teachers will intervene in bullying situations. (Contains 2 tables and 3 figures.)