The current study attempts to clarify the multi-faceted nature of impulsivity through the use of the four-factor UPPS Impulsive Behaviour scale. In order to build the nomological network surrounding this scale, the UPPS was administered to individuals with borderline personality disorder (BPD), pathological gamblers (PG), alcohol abusers (divided into two groups based on the presence of antisocial features), and a control group. Several of the UPPS scales (e.g. Urgency, lack of Premeditation, and Sensation Seeking) differentiated the BPD, PG, and alcohol abusers with antisocial features from a group of non-antisocial alcohol abusers and a control group. Overall, the UPPS scales accounted for between 7% (pathological gambling) and 64% (borderline personality disorder features) of the overall variance in the psychopathology measures. Individual UPPS scales also made unique contributions to several of these disorders, which may provide insight into which of these personality traits may predispose individuals to behave in maladaptive or problematic ways. The results provide support for the differentiation of impulsivity-related constructs into the current four-factor model. Copyright © 2005 John Wiley & Sons, Ltd.