Young victims and witnesses are being "left to flounder" in the criminal justice system, a report has found.
Vulnerable under-18s are not given the opportunity to give evidence by videolink or in written statements, and are told not to speak frankly to counsellors, according to inspectors.
The joint report by Her Majesty's Crown Prosecution Service Inspectorate (HMCPSI) and Her Majesty's Inspectorate of Constabulary (HMIC) explored the progress made after a similar review three years ago, but it uncovered some key failings in an "imperfect system".
The report - Experience of Young Victims and Witnesses in the Criminal Justice System - did find some cases of improvement after recommendations made in the 2009 report, A Joint Thematic Review of Victim and Witness Experiences in the CJS.
However, the joint inspection team found that only "limited progress had been made".
Special measures to ensure young victims and witnesses are as comfortable as possible in the criminal justice system need to be improved and offered more widely, inspectors found.
The report said "presumptions are often made on behalf of young witnesses", which leads to inappropriate decisions.
Options of video-recorded interviews for very young children or victims of sexual offences should be explained more clearly, and frontline police officers need to consider the way in which statements are taken and how subsequent trials could be affected.
Inspectors also found "mixed and conflicting attitudes to the access of young victims to therapy and counselling".
The report said: "Young victims are often traumatised by their experiences and need early access to therapy, including counselling.
"However some investigators reported that prosecutors had instructed them not to provide details of the offence to counsellors, but the counsellors were unable to help the child without discussing aspects of the case."
Concern was also expressed because some witness care units (WCUs) ignored guidance by trying to assess the needs of vulnerable witnesses by post rather than face-to-face.
The report criticised the police for failing to provide "timely and accurate information" to WCUs, which added to the difficulty of providing a quality service.
Inspectors interviewed representatives of the judiciary, staff responsible for dealing with young victims and witnesses, members of Victim Support (VS) and the Young Witness Service (YWS).
They also spoke to a number of young victims and witnesses directly and conducted file examinations of recently completed cases.
HMCPSI chief inspector Michael Fuller said: "The criminal justice system pledged back in 2007 to put victims at its heart, young victims and witnesses are amongst the most vulnerable of these.
"Although we found some excellent examples of good work, too often in the most serious of cases young people were not served well.
"Young people are being left to flounder in an imperfect system. The way the interests of young people are considered must improve and their interests must be taken seriously."
HM Inspector of Constabulary Dru Sharpling said: "The recommendations and examples of good practice in this report capture the best of the system and aim to promote its consistent delivery.
"It is key to the criminal justice system that young people have the confidence to report a crime and are then supported throughout the process of appearing as witnesses."