Background: Impulsivity is a hallmark characteristic of substance use disorders (SUDs). Recently, studies have begun to explore whether increased impulsivity in substance-dependent individuals (SDI) is associated with a greater propensity to relapse following treatment. Despite growing recognition of its multidimensional nature however, most studies have treated impulsivity monolithically. Accordingly, it remains unclear whether certain facets of impulsivity are more relevant to relapse than others. The aim of the current study was to examine the relationship between multiple facets of impulsivity and post-treatment relapse in SDI. As a secondary aim, we explored the role of treatment retention in this relationship. Methods: A personality-based impulsivity questionnaire (UPPS) and three neurocognitive tasks of impulsivity [stop signal task (SST), delay discounting task (DDT) and iowa gambling task (IGT)] were administered in a heterogeneous sample of 70 SDI shortly following their entry in an inpatient detoxification program. Mediation analyses were performed to explore whether the effects of impulsivity on relapse were mediated by treatment retention. Results: Performance on two neurocognitive indices of impulsive choice (i.e., DDT and IGT) was significantly associated with relapse and outperformed personality-based trait measures of impulsivity in predicting relapse propensity. The effects of delay discounting and impulsive decision-making on relapse propensity were mediated by treatment retention. Conclusions: Neurocognitive indices of impulsivity may be more promising in the prediction of relapse than trait-based self-report questionnaires. Post-treatment relapse in SDI may be reduced by targeting the processes involved in impulsive choice and by improving treatment retention in SDI with inflated impulsivity.