The purpose of this study was to identify factors that are predictive of, or associated with, postconcussion symptom reporting after traumatic brain injury (TBI) in the U.S. military. Participants were 125 U.S. military service members (age: M=29.6 years, standard deviation [SD]=8.9, range=18-56 years) who sustained a TBI, divided into two groups based on symptom criteria for postconcussional disorder (PCD): PCD-Present (n=65) and PCD-Absent (n=60). Participants completed a neuropsychological evaluation at Walter Reed Army Medical Center (M=9.4 months after injury, SD=9.9; range: 1.1 to 44.8). Factors examined included demographic characteristics, injury-related variables, psychological testing, and effort testing. There were no significant group differences for age, sex, education, race, estimated premorbid intelligence, number of deployments, combat versus non-combat related injury, or mechanism of injury (p>0.098 for all). There were significant main effects for severity of body injury, duration of loss of consciousness, duration of post-traumatic amnesia, intracranial abnormality, time tested post-injury, possible symptom exaggeration, poor effort, depression, and traumatic stress (p<0.044 for all). PCD symptom reporting was most strongly associated with possible symptom exaggeration, poor effort, depression, and traumatic stress. PCD rarely occurred in the absence of depression, traumatic stress, possible symptom exaggeration, or poor effort (n=7, 5.6%). Many factors unrelated to brain injury were influential in self-reported postconcussion symptoms in this sample. Clinicians cannot assume uncritically that endorsement of items on a postconcussion symptom checklist is indicative of residual effects from a brain injury.