Desperate officials from health, education and social services are sometimes failing to disclose the full range of a student's problems because there is nowhere else available, say researchers from the London School of Economics.
In other cases, the agencies are themselves unaware of the problems, thanks to inadequate assessment or poor communication. Problems left unreported include violent behaviour and abuse, and fire setting, according to research.
"Residential providers are frequently asked to provide 24-hour specialist care and treatment for highly-damaged children and young people, with often only the barest background details or assessments of what is needed," according to Dr Catherine Street. She interviewed staff at 43 residential institutions, including 13 special schools, for her research.
"Such a situation is hardly conducive to a successful placement for a young person and the optimal use of a scarce and costly resource," she says.
Demand for emergency placements was "relentless," and schools were taking in young people with long histories of difficulties and previous, unsuccessful, placements. Often, excluded young people had been left without education for a year or more before getting residential placements.
Karen Thornton Dr Street can be contacted at the New Policy Institute, tel: 0171 721 8421.