Impulsivity, a breakdown in the balance between initiation and screening of action that leads to reactions to stimuli without adequate reflection or regard for consequences, is a core feature of bipolar disorder and is prominent in manic episodes. Catecholaminergic function is related to impulsivity and mania. Manic individuals have abnormal dopaminergic reactions to reward and abnormal responses in the ventral prefrontal cortex that are consistent with impulsive behavior. Impulsivity in mania is pervasive, encompassing deficits in attention and behavioral inhibition. Impulsivity is increased with severe course of illness (eg, frequent episodes, substance use disorders, and suicide attempts). In mixed states, mania-associated impulsivity combines with depressive symptoms to increase the risk of suicide. Clinical management of impulsivity in mania involves addressing interpersonal distortions inherent in mania; reducing overstimulation; alertness to medical-, trauma-, or substance-related problems; and prompt pharmacologic treatment. Manic episodes must be viewed in the context of the life course of bipolar disorder.