The Howard League for Penal Reform has won £2.6m lottery money to set up a national programme of legal support for young people in custody.
The service, called UR Boss, will advise young people on challenging legal decisions, give guidance on their entitlements during detention and after release and media training.
The charity said the five-year project would aim to give a voice to disenfranchised and neglected young people in prisons.
Howard League director Frances Crook said: “Our legal team’s case files tell the stories of neglected and abused children, with chaotic family backgrounds and problems ranging from mental health needs to drug or alcohol addictions. Too often local authorities and other agencies have failed these young people from a very early age.”
Crook said helping young people to address the causes of their offending would reduce the risk of crime.