Despite longstanding agreement that violence committed by people with mental ill health is relatively low, the relationship between mental health and offending remains an area of contention. In recent times, this debate has featured prominently in the UK, France, Australia, New Zealand and the United States in relation to what are ostensibly instances of religious and politically motivated violence. In such cases, the process of ‘radicalisation’, whereby individuals are inculcated into accepting extremist ideology, has been defined as a critical precursor to violent action. Drawing on case studies in various global locales, this chapter unravels the complicated connections in this domain and excavates the perils that arise in establishing causal connections between extreme violence and psychological and behavioural disorders. To conclude, we echo patterns in other contexts and contend that mental illness is becoming an explainer that obscures the role of structural factors that may push individuals towards violence.