The wave of Islamic State-linked terrorism experienced in the West over the past couple of years has rekindled debates surrounding mental disorders and terrorist engagement. A very preliminary survey by the authors found that out of 55 attacks in the West where the 76 individuals involved were possibly influenced by the Islamic State, according to media reports, 27.6% had a history of apparent psychological instability, a percentage comparable to that found in the general population. This figure is driven largely by individuals inspired by the Islamic State, as opposed to those directed by it, however. The percentage is likely overinflated for several noteworthy reasons, including poor reporting, low benchmarks, and the tendency to overuse mental health problems as a ‘silver-bullet’ explanation for terrorist involvement. The relationship is, in fact, far more complex than typically presented.