During four decades, numerous school-based bullying prevention programmes have been developed and evaluated. Meta-analyses indicate that such programmes have positive average effects, as compared with treatment as usual. However, the effects are small to moderate, and they are especially weak among some specific groups, such as adolescents. After all the progress made, too many young people still suffer from being bullied. Furthermore, findings suggest that the remaining victims may be even worse off than before in contexts where the overall level of victimization decreases -- the phenomenon known as the "Healthy Context Paradox." It is suggested that besides the average effects of preventive, universal multi-component programmes, more attention should be devoted to targeted interventions addressing specific cases of bullying. More precisely, we should investigate "the characteristics and conditions of youth who remain victimized or continue bullying others despite targeted interventions," and identify factors -- at multiple levels -- that are related to intervention failure.