Traumatic brain injury (TBI) may affect 10 million people worldwide. It is considered the "signature wound" of the conflicts in Iraq and Afghanistan. These injuries result from a bump or blow to the head, or from external forces that cause the brain to move within the head, such as whiplash or exposure to blasts. TBI can cause an array of physical and mental health concerns and is a growing problem, particularly among soldiers and veterans because of repeated exposure to violent environments. One form of treatment for TBI is cognitive rehabilitation therapy (CRT), a patient-specific, goal-oriented approach to help patients increase their ability to process and interpret information. The Department of Defense asked the IOM to conduct a study to determine the effectiveness of CRT for treatment of TBI.