Vulnerable children are not being given refuge in boarding schools as too few local authorities have relevant expertise, a government-backed study has found.
Councils must overhaul their systems if pupils at risk of going into care are to benefit from the education and pastoral support offered by boarding, the Government and headteachers have been told.
Ministers are keen to use private and state boarding schools to house vulnerable children. More than 50 boarding schools - state and private - signed up to a pathfinder project last year, but it has failed to place as many children as had been hoped.
About 40 were supposed to have been given places in schools in September 2007, but only about 10 were finally assigned places. By last June, 15 had been placed. A study by academics at London's Institute of Education is due to be published in January.
But its interim findings, which highlight the changes local authorities need to make, have been presented to officials.
The full report, which had been due this year, was pushed back to allow for an evaluation of how pupils cope with the transition between term-time and holidays, when many return to their families.
Some boarding schools already offer places to vulnerable pupils, administered and paid for through schools' own charitable trusts.
The Royal Alexandra and Albert School in Surrey funds 49 of its 400 boarders who are at risk of going into care. Head Paul Spencer Ellis believes the model should be replicated nationwide.
Melvyn Roffe, principal of Wymondham College, a state boarding school in Norfolk, said hundreds of vulnerable pupils were benefiting from boarding, but on an "ad hoc" basis.
"Vulnerable children do not have equal access to boarding," he said. "The block is that it has taken longer than we thought for local authorities to look at boarding for vulnerable children and get their systems in place."
He said local authorities needed to build better relationships with boarding schools so that the option of placing pupils there was considered more regularly than it is now.
He also urged local authorities with know-how to share it widely so that more pupils could benefit.
Research published last year by the Royal Wanstead Children's Foundation found that vulnerable children thrive academically in boarding schools.
Some academies are also interested in offering boarding to pupils at risk of going into care but have found it difficult to fund the places.