Severe and long-term bullying causes psychological distress which impacts the physical and psychological well-being of bullied victims and can cause impairment in all aspects of life. As a clinician experienced in working with victims of terrorist bombings, major rail crashes, armed raids, rape, traffi cking, body recovery, armed confl ict and other major traumas, it was surprising initially to fi nd that victims of bullying were suffering very similar symptoms and in the most extreme cases the symptoms had a more profound impact on their psychological and physical health and wellbeing. This chapter looks at the history and need for accurate diagnosis and classifi cation of psychiatric conditions and the development of the diagnosis of post-traumatic stress disorder (PTSD). The controversy that surrounds this unusual diagnosis and the need to maintain boundaries to protect the disorder from trivialisation and overuse is described. The case for enabling severe bullying to be recognised under Criterion A-1 is provided, supported by evidence from research into the impact of bullying. Finally, suggestions are made on ways to look at traumatic exposures and address some of the problems faced in the existing classifi cations.