Borderline personality disorder (BPD) and alcohol use disorder (AUD) share impulsivity as an etiological factor. However, impulsivity is ill-defined, often overlapping with self-control capacity. This study attempts to disentangle these constructs and their associations with alcohol use and BPD. Undergraduates (n = 192) completed the Five Factor Model Rating Form, which generated two-dimensional scales of BPD, the Self-Control Scale, the UPPS-P (self-reported impulsivity), and the stop-signal and delay discounting tasks (laboratory-measured impulsivity). Self-control appeared as a major predictor of BPD features and drinking, explaining as much or more variance in outcome than impulsivity. Co-occurrence of elevated BPD features and problem drinking was also best explained by self-control. Laboratory measures of impulsivity were not correlated with BPD scales or alcohol use. Self-regulatory capacity may be an important but overlooked factor in BPD and alcohol use and should be considered alongside impulsivity in future research.