The majority of education authorities in England do not have a written policy on dealing with children who are missing school, research shows.
Only 17% of LEAs have a written policy on children missing education
Officially it is estimated that 10,000 children in England are missing school.
But a government study found 58% of authorities did not have a database of children who are not registered at a state school or being taught elsewhere.
And many had difficulties persuading schools to take on these children once they were identified.
The concern over children missing out on schooling has been highlighted by the Every Child Matters policy.
These children are defined as "not on a school roll, nor being educated otherwise (e.g. privately or in alternative provision").
In 2002 the Department for Education and Skills set a target that "by December 2005, every local authority should have systematic arrangements in place to identify children missing from education, so that suitable provision can be made for them".
But a poll conducted in March by the private consultancy Creative Research on behalf of the department found only 17% of the 129 LEAs that responded had a written policy concerning children missing education.
Just 44% had identified the ways in which children in their authority became "missing" and had put procedures in place to close those gaps.
And 58% did not keep a record of children who had left schools or alternative provision "with a known destination".
The research also found many authorities had difficulty persuading schools to enrol these children if they are found.
These children were often perceived as "difficult" cases, such as children with special educational needs, with English as a second language or with behavioural, emotional and social difficulties.
"In many instances local authorities find it very difficult to place these types of cases and the schools are often seen as putting up major barriers," the report said.
A spokesman for the Department for Education said any child missing from education was a concern - not just for the child's educational attainment, but also for his/her safety and welfare.
"Children dropping out of the system should be brought back in more swiftly and re-engaged with learning," he said.
"That is why the Education and Inspections Bill proposes a new statutory duty on all local authorities to make arrangements to identify children missing education."