This research developed and evaluated a measure to examine fire-specific constructs relevant to fire misuse. In the first study, using UK community members asked to disclose deliberate firesetting, we tested a large pool of theoretically informed questionnaire items. First, we found that 1 in 10 adults reported setting a deliberate fire that they had not been apprehended for. Then, exploratory and confirmatory factor analyses suggested an eight-factor measure with broader coverage of theoretically-informed risk factors, relative to previous measures, and acceptable test item validity and robust internal consistencies. In the second study, we tested the Firesetting Questionnaire with imprisoned men who held a record of firesetting and imprisoned and community comparisons. The findings illustrated psychometric robustness. Our results suggest that the Firesetting Questionnaire has the potential to be a useful clinical tool for highlighting fire-specific treatment needs and informing clinical formulation and associated risk management.