Emotion processing in the brain produces asymmetrical cortical activity in the left and right prefrontal regions, dependent on the emotional stimuli used. Empirically supported but competing hypotheses explain this phenomenon using qualities of the emotion that characterize either its valence (positive or negative) or its motivation potential (approach or avoid).The emotional stimuli used are often confounded in that both positive affect and approach-oriented emotions have been positively associated with increased left prefrontal activity, and negative affect and avoidance-oriented emotions have been positively associated with increased right prefrontal activity. Anger, which is negative in valence and approach-oriented, disentangles previous confounds and positively relates to left frontal activity, supporting the motivation hypothesis of prefrontal asymmetry in emotion processing. This body of research was extended to the parenting context to test whether left frontal asymmetry is associated with anger and interpersonal aggression. Forty mothers of children 2-4 years of age completed measures of anger, parental discipline, and an analog-parenting task while EEG data was recorded. Based on data linking greater left frontal cortical activity and approach-oriented motivation, it was hypothesized that (1) greater dispositional anger, and harsh discipline style in mothers would be positively related to greater left frontal activity at baseline; (2) greater dispositional anger would predict greater state related left frontal activity in the analog parenting task; (2a)harsher discipline styles would account for unique variance in state related left frontal activity; and (3) greater left frontal activity at baseline would predict greater reported anger and more harsh discipline responses from mothers following the misbehavior video. Partial support was found for these hypotheses. Trait anger is an important aspect of harsh overreactive discipline and was related to greater activation in the left frontal area of the brain during an anger evoking parenting context. No relationship was found between resting frontal asymmetrical activity and the other study variables. These findings may be translated into specific risk models or differential intervention approaches for parents with motivation sensitivity struggling with maladaptive discipline responses.