Forest fires in Italy are mainly caused by humans, and directly depend on social behavior, whether voluntary (arson) or involuntary (negligence). Despite the progress in knowledge made with studying the physical facets of the phenomenon, causes and motives of human-related fire remain mostly unknown. This paper proposes the implementation of the Delphi method (an interactive expert-questionnaire process) in order to assess why fires are ignited. In four study cases, within a high fire incidence area (southern Italy), the Delphi technique identified as major cause of negligence the use of fire in agriculture and, as major causes of voluntary fires, motives related to seasonal labor. The main results in terms of frequency are: (i) for involuntary events (negligence), experts unanimously identified the relevant importance of negligent use of agricultural fires, particularly stubble burning (13.99% of responses). For (ii) voluntary fires (arson), results highlight the relative importance of fires ignited by seasonal workers as an instrument to force or maintain employment (8.41% of responses). © SISEF.