Children and young people in the criminal justice system in England are drawn, in the main from the most deprived and disadvantaged families and communities. Many will have experienced neglect, abuse, domestic violence, poor parenting and poor educational opportunities. It is then perhaps unsurprising that behavioural and mental health difficulties, learning disabilities and conduct disorders are prevalent among these children and particularly those who are detained in our custodial institutions. While it is to be commended that the number of children entering the youth justice system is declining, nevertheless England continues to lock up more young people aged 10 to 17 than almost any other European country. Organisations in the youth justice system face the difficult and complex task of balancing custody with care. It would not be unreasonable to expect that in order to both protect the public and help children and young people in the criminal justice system to change their lives and prospects, the services and care provided for them in the system would be designed to promote emotional wellbeing, treat any disorders and rehabilitate as well as address their offending behaviour. Therefore, throughout 2010 the Office of the Children’s Commissioner observed and examined the treatment of and services provided to children and young people in the criminal justice system to address their emotional and mental health needs. This report contains the *findings and recommendations*arising from this work.