Impaired control over alcohol is an important risk factor for heavy drinking among young adults and may mediate, in part, the association between personality risk and alcohol problems. Research suggests that trait impulsivity is associated with impaired control over alcohol; however, few studies of this association have included a range of impulsivity facets. The purpose of this study was to examine specific pathways from higher order impulsivity factors to alcohol problems mediated via impaired control over alcohol. We also examined the moderating role of working memory in these associations. Young heavy drinkers (N = 300) completed 2 multidimensional impulsivity measures along with self-report measures of impaired control over alcohol, alcohol use, and alcohol problems. Working memory was assessed using a computerized digit span task. Results showed that the impulsivity facets loaded onto 2 higher order factors that were labeled Response and Reflection Impulsivity. Response impulsivity predicted unique variance in self-reported impaired control and alcohol problems, whereas reflection impulsivity predicted unique variance in heavy drinking frequency only. Further, significant indirect associations were observed from response and reflection impulsivity to alcohol problems mediated via impaired control and heavy drinking frequency, respectively. Working memory and sensation seeking were not uniquely associated with the alcohol variables, and no support was found for the moderating role of working memory. The results help to clarify associations among impulsivity, impaired control, and alcohol problems, suggesting that impaired control may play a specific role in the pathway to alcohol problems from response impulsivity but not from reflection impulsivity.