Neuroscientific evidence indicates that human social functioning is supported by a distributed network of frontal and temporal brain regions that undergoes significant development during childhood and adolescence. Clinical studies of individuals with early brain insults (EBI) to frontotemporal regions suggest that such lesions may interfere with the maturation of sociocognitive skills and lead to increased sociobehavioural problems. However, little attention has focussed on the direct assessment of sociocognitive skills, such as moral reasoning, following focal EBI. In the present study, the performance of 15 patients with focal EBI (8-16 years) was compared to that of 15 demographically matched controls on basic neuropsychological measures (IQ and executive functions), sociocognitive tasks (moral reasoning, moral decision-making and empathy) and parent reports of sociobehavioural problems and social adaptive skills. Patients with focal EBI had significantly lower levels of moral reasoning maturity, moral decision-making, and empathy than their matched controls, but did not differ on more general measures of cognition. Their parents also reported increased sociobehavioural problems. These findings suggest that focal EBI to frontotemporal regions can result in reduced sociocognitive capacities, more specifically moral reasoning, and increased vulnerability to sociobehavioural problems.