PurposeRelatively little is known about the prevalence of traumatic brain injury (TBI) among adolescents who come into contact with the criminal justice system. MethodsWe undertook screening for TBI among newly admitted adolescents in the New York City jail system using a validated TBI screening tool. A convenience sample of 300 male and 84 female screenings was examined. ResultsScreening revealed that 50% of male and 49% of female adolescents enter jail with a history of TBI. Incidence of TBI was assessed using patient health records, and revealed an incidence of 3,107 TBI per 100,000 person-years. ConclusionsElevated prevalence and incidence of TBI among incarcerated adolescents may relate to criminal justice involvement as well as friction in jail. Given the large representation of violence as a cause of TBI among our patients, we have begun focus groups with them to elicit meaningful strategies for living with and avoiding TBI.