Traumatic brain injury (TBI) it is the leading cause of mortality and disability in young people. The key points of risk are pre-school – and mid-teenage to young adulthood, typically for males. Adversity and poverty of opportunity are risk factors for TBI. Symptoms of TBI are wide-ranging, but can include cognitive difficulties behavioural and/or mood-related changes. Important functions for learning, emotion regulation, self-control and social behaviour are often affected – particularly when the ‘social brain’ network is compromised. The effects of TBI can be very subtle, but often have wide and far-reaching consequences in both the short and longer-term. As brain systems are constantly evolving, injury may impair current, and future, abilities, by eroding their foundations. TBI increases the risk of social isolation, behavioural disorder and psychiatric morbidity. It may contribute to problems leading to school exclusion and to entry to the criminal justice system. Indeed, TBI is associated with earlier, more violent and persistent offending.