This study investigated the antecedents and psychological processes inherent in firesetting within an adult intellectually disabled population. A qualitative methodology, grounded theory (GT) was employed to explore the experience of firesetting through verbal self-report. A sample of eight males with mild intellectual disabilities under the care of forensic learning disability services participated in interviews which ranged from 27 minutes 14 seconds to 1 hour 21 minutes 22 seconds. The data produced a preliminary GT which identified eight conceptual categories: Managing internal affect states, the experience of adversity, unsafe others, engagement in multiple offending behaviours, voice entitlement, experiences of fire, and mediators of risk and the function of firesetting. These conceptual categories were linked by an overarching core category of ‘powerlessness’ which was evident in several areas of the participants’ lives and experiences of firesetting. It was concluded that this sense of powerlessness along with the conceptual categories should be considered when risk assessing, delivering firesetting specific treatment and psychological interventions. The clinical implications are discussed and suggestions are made for replication of the current study with larger, more diverse samples and future directions for further research are proposed.