This study examined the structure of impulsivity within gambling disorder. A group of 51 men and 53 women with gambling disorder completed self-report and behavioral measures of impulsivity. Principal component analyses found two factors. The first was interpreted as measuring trait impulsivity. This factor correlated with problem gambling severity, presence of comorbid mental health and substance use disorders, history of brain injury, and was higher in Aboriginal participants. The second factor had high loadings on the self-reported sensation-seeking scales and the behavioural measures of response impulsivity. This factor correlated with overall gambling involvement but not with indicators of pathology. Higher scores were associated with younger age. These results are consistent with an evolving model of the etiology of disordered gambling that suggests that sensation-seeking is related to gambling involvement but that trait impulsivity and mental health struggles are associated with the development of gambling disorder.