This study with 326 girls-school teachers developed and tested a model of predictors of the likelihood that teachers will intervene in indirect bullying, and evaluated a professional development presentation. Teachers responded to bullying vignettes before and after a presentation on indirect bullying (Experimentals) or adolescent mental health (Controls). In accord with the model, perceived seriousness of indirect bullying mediated between empathy for victims and likelihood of intervening. Self-efficacy also had a direct effect on likelihood of intervention, though level of knowledge of the impact of indirect bullying made only a small contribution. Compared with Controls, the Experimental Group scored more highly, after the presentation, on perceived seriousness of indirect bullying, empathy for victims, likelihood of intervening and self-efficacy, but not on knowledge of impact. It is concluded that teacher education about indirect bullying may be most effective if it focuses on feelings rather than facts, and provides practical intervention strategies.