The behavioral approach system (BAS) reflects the propensity to respond to signals of reward, including stimuli associated with safety and goal-oriented attack (e.g., anger). Hypomania/mania has been posited to involve increased BAS activity. In contrast, depression has been posited to involve decreased BAS activity. Building on past research, which suggests that increased left frontal cortical activity is a neurophysiological index of BAS activity, the present research tested the hypotheses that proneness toward hypomania/mania symptoms would be related to increased relative left frontal activity and that proneness toward depression symptoms would be related to decreased relative left frontal activity in response to an anger-evoking event. Results from 67 individuals who had completed a measure of proneness toward these affective symptoms and were exposed to an anger-evoking event supported the hypotheses.