This study investigated whether executive dysfunction and impulsivity are both predictors of reactive aggression and is the first to use behavioral assessment of aggression in response to provocation by means of a personalized boxing body opponent bag giving harassing feedback. Aggressive behavior, self-reported aggression, executive functioning (ie, working memory, flexibility, and divided attention), and impulsivity dimensions (i.e., Sensation Seeking, Impulsive Decision Making, and [inadequate] Response Inhibition) were measured in 44 incarcerated psychiatric patients. Results show that both executive functioning (working memory) and impulsivity (Impulsive Decision Making) predicted self-reported reactive aggression, whereas Response Inhibition was the only predictor for reactive aggressive behavioral responses. The study suggests that Response Inhibition is a stronger predictor of reactive aggressive behavior than executive capacities of working memory, flexibility, and divided attention. Therefore, future research should investigate whether (inadequate) Response Inhibition could also be a valuable predictor for violent recidivism.