Pediatric traumatic brain injury (TBI) is a major public health problem. Psychiatric disorders with onset before the injury are more common than population base rates. Novel (postinjury onset) psychiatric disorders (NPD) are also common and complicate child function after injury. Novel disorders include personality change due to TBI, secondary attention-deficit/hyperactivity disorder, other disruptive behavior disorders, and internalizing disorders. This article reviews preinjury psychiatric disorders as well as biopsychosocial risk factors and treatments for NPD.