The Theory of Planned Behavior (Ajzen, 1991) states that behavioral intention is the strongest determinant of human behavior. Impaired control (IC; Heather et al., 1993) reflects an intentional failure to consume less alcohol. Cross-sectional studies suggest that IC may mediate relations between impulsivity facets and drinking outcomes but there is only one prospective study examining ICS-Failed-Control (Leeman et al., 2009) and it did not account for effects of impulsivity-facets. Our study sought to address this gap in the literature by examining ICS-Failed-Control as a mediator of relations between impulsivity facets and alcohol-related consequences. We fit a three-wave cross-lagged panel model in a sample of 448 young adults (21–23) from an alcohol challenge study with longitudinal follow-ups (6 and 12 months). Participants completed the UPPS-P, TLFB Interview, the ICS-Failed-Control scale and the YAACQ. Although IC did not mediate effects of impulsivity on alcohol consequences, IC significantly predicted changes in alcohol-related problems at the12-month follow-up, accounting for effects of UPPS-P constructs as well as alcohol use. Lack of premeditation predicted change in alcohol use from baseline to 6-month follow-up and alcohol use (at 6-months) mediated the effect of premeditation (at baseline) on alcohol consequences (at 12-months). Our findings suggest that ICS-Failed-Control is not a mediator of the effects of impulsivity but is a unique predictor of consequences. Future studies should assess UPPS-P constructs earlier in adolescence to identify potential prospective links between UPPS-P constructs and IC.