Greater left frontal activation appears to be a measure of appetitive reactivity for desired stimuli, such as alcohol cues. However, inconsistencies in past research examining frontal asymmetry to appetitive stimuli suggest that individual differences strongly influence frontal asymmetry to appetitive stimuli. Because core personality systems of approach, avoidance, and supervisory control play a fundamental role in directing alcohol behavior, the current study sought to determine which core system would influence asymmetric frontal activation to alcohol cues. Results revealed that greater trait impulsivity (reduced functioning of the supervisory control system) is related to greater relative left frontal activation in response to alcohol cues. Approach motivation and avoidance motivation were unrelated to greater relative left frontal activation in response to alcohol cues. These results suggest that decreased activation of the supervisory control system (increased trait impulsivity) is responsible for appetitive reactivity to alcohol cues.