Disinhibition, the inability to inhibit inappropriate behavior, is seen in frontal-temporal degeneration, Alzheimer's disease, and stroke. Behavioral disinhibition leads to social and emotional impairments, including impulsive behavior and disregard for social conventions. The authors investigated the effects of lesions on behavioral disinhibition measured by the Neuropsychiatric Inventory in 177 veterans with traumatic brain injuries. The authors performed voxel-based lesion-symptom mapping using MEDx. Damage in the frontal and temporal lobes, gyrus rectus, and insula was associated with greater behavioral disinhibition, providing further evidence of the frontal lobe's involvement in behavioral inhibition and suggesting that these regions are necessary to inhibit improper behavior.