Traumatic brain injury (TBI) is a major health problem affecting thousands of Canadians and their families each year. Little is known about the long-term consequences of pediatric mild traumatic brain injury (MTBI) on psychological functioning in adulthood. There are two major perspectives on this topic. The Kennard Principle asserts that young brains are more plastic and thus better suited to compensate following injury. The Early Vulnerability Hypothesis challenges this assertion with the idea that early damage to the brain may have significant implications for emerging cognitive and social skills. Executive function and social competence are skills that may be especially vulnerable to impairment following head injury in children. Executive function and social competence rely on frontal neural networks, which are particularly vulnerable to damage from MTBI. As frontal regions underlying executive functions and social competence are slower to mature, the outcome of these faculties following pediatric TBI cannot be accurately assessed until brain maturity has been reached. The present study thus examined the consequences of pediatric MTBI on executive functions and social skills in adulthood. Participants were undergraduate students from the University of Regina. A screening survey was administered to 1295 students to identify individuals with a history of head injury and those without. The study sample consisted of 24 participants with a history of head injury (HI) and 29 participants with no history of head injury. The average age of both groups approximated 20 years and the average time since injury for the HI group was 10.5 years. A comprehensive battery of executive functioning, emotion recognition, and psychosocial measures was administered to the participants. The principal results of the study revealed a statistically significant difference between the HI and Control group on the Global Deficit Score (GDS; a composite score computed using 22 individual objective and demographically-corrected tests of cognitive function), with the HI group also falling above the clinical cut-off for neuropsychological impairment on this measure. In addition, the GDS demonstrated an overall moderate level of diagnostic accuracy when evaluated using Receiver Operating Curve analysis. In terms of the individual objective cognitive tests, the HI group performed significantly more poorly on the PASAT compared to the Control group, suggesting particular difficulties in the areas of auditory attention and working memory, findings characteristic of executive dysfunction and the known pathophysiology of traumatic brain injury. On the Neuropsychological Impairment Scale, a broad-based self-report measure, the HI group endorsed significantly more symptoms of somatic and cognitive dysfunction than the Control group. Taken together, these results are consistent with the Early Vulnerability Hypothesis and suggest that childhood MTBI may be associated with subtle objective deficits in executive function, along with elevated somatic and cognitive symptomology in adulthood.