Approximately half of local authorities need to improve their services for cared-for children, education inspectors have said.
Too many children in care have poor school attendance, Ofsted said
Ofsted said they should focus on their attendance and help them attain highly.
Their report on children's services said there was a "worrying gap" in performance between authorities in key areas of education services.
But more than 60% of authorities provide social care which is consistently above minimum standards.
Areas of education services which authorities should focus on include school attendance and key stage 4 attainment (16 years).
Ofsted's report said local authorities must focus on ensuring that looked-after children attend school and attain highly, ensure they are placed in long-term stable care, and increase the number of adoptions.
For the fifth successive year, one in eight local authority cared-for children missed at least 25 school days.
"Although looked-after children are well supported and achieve good outcomes in about half of authorities, they are inadequately supported and achieve low outcomes in almost the same proportion," the report said.
Further improvement at key stage 4 level was needed in about four in 10 authorities.
Ofsted's report is an annual performance assessment of children's services in 2005, which evaluated 147 authorities.
The report says three quarters of councils deliver educational services which are consistently above, or well above, minimum requirements.
The best examples feature a strong partnership between schools and support services.
The report says many local authorities have good strategies for reviewing child protection cases, reducing the rates of offending by children and young people and promoting healthy lifestyles in schools.
Ofsted chief inspector of schools Maurice Smith said: "More must be done to improve the life chances of certain groups of young people, particularly looked after children, and councils will need to demonstrate sustained improvement."
But councillor Les Lawrence, the chair of the Local Government Association children and young people board, said local authorities should be congratulated for the services they provide with tight budgets.
"But there is no room for complacency," he said. "All councils should be meeting the highest standard possible.
"The LGA and its partners are aware that improvement is needed in some areas, which is why they have been identified as priorities for LGA work."