<p>The firesetting literature has predominantly focused on apprehended populations, yet very few perpetrators of deliberate fire incidents are formerly identified or convicted. This research aimed to gather a deeper understanding of un-apprehended firesetting individuals by examining the prevalence of deliberate firesetting in the Aotearoa New Zealand general population, as well as the factors that differentiate between (i) firesetting and non-firesetting individuals, (ii) one-time and repeat firesetting individuals, and (iii) adolescent-limited, adult-persistent, and adult-only firesetting individuals. An anonymous online survey was completed by 626 adults, of which 103 (16.45%) self-reported having deliberately set a fire over the age of 14 years for antisocial or interest purposes. Relative to non-firesetting individuals, firesetting individuals were more likely to report having a high school qualification as their highest educational attainment, a history of a mental health diagnosis, and higher scores on measures of fire-interest, impulsivity, fearful attachment styles, anger, and antisocial associates. The strongest predictor of firesetting status was holding a high school qualification as the highest educational attainment. Relative to one-time firesetting individuals, repeat firesetting individuals were more likely to be older at their last incident of deliberate firesetting and scored higher on measures of fire interest, with age at last deliberate firesetting incident being the strongest predictor of repeat firesetting status. Finally, adolescent-limited, adult-persistent, and adult-only firesetting individuals could be differentiated on number of fires set and ages at first and last deliberate firesetting incidents. The strongest predictor of adult-persistent firesetting status was having a history of a mental health diagnosis. These findings greatly advance our understanding of un-apprehended firesetting behaviour; highlighting the need for tailored, multifaceted prevention initiatives, and theories specific to the unique population of un-apprehended firesetting individuals.</p>