This mixed-methods study examined elementary teachers' perceptions of teacher-student bullying. Grounded in previous research on peer bullying, the study posed several questions: to what extent did teachers perceive bullying of students by other teachers as a serious matter requiring intervention? Did they perceive teacher bullying as more serious than peer bullying, and did their perceptions differ by the nature of the bullying incident? Findings indicate that teachers are aware of isolated and ongoing student bullying by their colleagues; however, they have a higher sense of accountability for peer bullying and forms of bullying with physical rather than socio-emotional consequences. Teachers' sense of accountability was correlated with years of experience but unrelated to participation in professional development, despite sustained anti-bullying initiatives over a 10-year period. (Contains 4 tables.)