Psychiatric disorders frequently complicate recovery and rehabilitation from traumatic brain injury (TBI). This study reviews the literature from 1978 to 2006 on psychosis, depression, posttraumatic stress disorder, mania, and aggression following nonpenetrating TBI. The studies were reviewed using the American Academy of Neurology's criteria for classification of articles on diagnostic methods. No studies were found to be Class I or II. Of the 66 studies reviewed, the majority were Class IV. There are significant gaps in the literature on post-TBI psychiatric conditions with respect to nosology, epidemiology, and risk factors. Larger multicenter prospective studies using standardized diagnostic instruments are needed to further clarify the nosology, risk factors, and clinical course of these disorders. Specific directions for research are provided.