Previous research in Australia and overseas has shown that young offenders serving community-based orders are at high-risk for undetected but clinically significant oral language difficulties. However, this phenomenon has received little attention in incarcerated samples, and links with offending severity, mental health, and other markers of early risk have not previously been systemically examined. A cross-sectional examination of 100 young offenders (mean age 19.03 years) completing custodial sentences in Victoria, Australia was conducted. A range of standardized oral language, IQ, mental health, and offending severity measures was employed. Forty-six per cent of participants were classified as language impaired (LI), and these were compared with the non-LI sub-group on background and offending variables. When the sub-group with high scores on a measure of offending severity was compared with those with (relatively) lower offending scores, significant differences on a range of language measures were identified. A range of early risk indicators (such as placement in Out of Home Care) was also examined with respect to language impairment in this high-risk group. Results are discussed with respect to policy and practice pertaining to early intervention for vulnerable children, and implications for service delivery within the justice system. In particular, emphasis is placed on the need to closely examine the oral language skills of children who struggle with the transition to literacy and then display behavioural difficulties in the classroom. Once a young person is engaged with youth justice services, a high index of suspicion should be maintained with respect to their oral language skills; for example, in relation to forensic interviewing and the ability to benefit from verbally mediated interventions.