Whiteside and Lynam (Whiteside, S. P., & Lynam, D. R. (2001). The Five Factor Model and impulsivity: Using a structural model of personality to understand impulsivity. Personality and Individual Differences, 30, 669-689) clarified the multifaceted nature of impulsivity by identifying four distinct facets of self-reported impulsive behaviors: urgency, (lack of) premeditation, (lack of) perseverance, and sensation seeking. Building on work by Bechara and Van der Linden (Bechara, A., & Van der Linden, M. (2005). Decision-making and impulse control after frontal lobe injuries. Current Opinion in Neurology, 18, 734-739), the main objective of this study was to investigate the hypothesis that perseverance and urgency map onto the two distinct inhibitory functions distinguished by Friedman and Miyake (Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: A latent-variable analysis. Journal of Experimental Psychology: General, 133, 101-135): prepotent response inhibition and resistance to proactive interference. Participants (N=126) completed the UPPS Impulsive Behavior Scale and three tasks: a recent-negatives task to assess proactive interference in working memory, and two Go/No-Go tasks at different paces, the slower of which also assessed task-unrelated thoughts (TUTs). Consistent with the hypothesis, TUTs were positively correlated with lack of perseverance, and multiple regressions revealed that urgency was specifically related to errors in prepotent response inhibition, and lack of perseverance to errors due to difficulties overcoming proactive interference.