Bullying has been described as the most tractable risk factor for poor mental health in children and adolescents. Over 25% of UK children report being bullied at least weekly and are more likely to experience depression and anxiety, have reduced school attendance and do less well academically than children who do not experience bullying. Yet whilst every school in the UK is obliged to have an anti-bullying policy in place, there is very little guidance of what are the best evidence-based interventions to implement. In this talk I discuss a new collaborative research program aiming to evaluate whether an intervention developed and taken to scale in Finland (KiVa) might also work here in the UK. I will also describe new research in our lab that is aiming to develop a virtual-reality based intervention for adolescents who have already experienced bullying and are at-risk of developing poor mental health.