Although anti-bullying programs often include a component that focuses on strengthening teachers' abilities in identifying and addressing bullying, it is not clear which bullying situations teachers find difficult to address and what type of support is needed. In the current qualitative study, we investigated what teachers considered difficult bullying situations, how they responded to these situations, and which barriers they encountered. We used data from individual in-depth interviews conducted with 38 Dutch elementary school teachers. Qualitative analysis showed that teachers experienced difficulties in (a) identifying bullying that happens out of sight, (b) estimating the seriousness of a reported incident, (c) addressing persistent aggressive and bullying behavior, and (d) finding solutions with parents to reduce bullying. Teachers used a variety of strategies in their efforts to address these situations. The results give insight into teachers' needs regarding specific training and support in anti-bullying programs and preservice teacher programs.