Thousands of children are missing from the education system, a charity has warned.
Many youngsters are losing out because they do not have a school place, or are simply unknown to the authorities, according to research by the National Children's Bureau (NCB).
The findings, based on Freedom of Information (FOI) requests to local councils in England, show that across 79 authorities, on any given day 7,701 youngsters are recorded as missing education.
The NCB said that based on this figure, it estimates that more than 14,800 children are not in education at any one time across the country.
A further analysis, based on detailed FOI responses from 45 councils, suggests that on any given day, of those who are missing education, there are an estimated 3,000 youngsters across England whose whereabouts are unknown and equivalent to almost 5,000 children who are losing out because they are waiting for a school place.
Other reasons given for children being classed as "missing" education include being excluded from school, special educational needs, being pregnant or a teenage mother, because the youngster is not enrolled in school or is moving between schools, or because they have moved, or are believed to have moved overseas.
Children are considered to be missing education if they are not on a school roll and not receiving suitable education other than at school, according to guidance.
The NCB said it was calling for the Government to conduct a national review of children missing education.
The charity's chief executive, Dr Hilary Emery, said: "Children who miss out on education are at significant risk of failing academically, and may end up as NEETs (not in education, employment or training) in later life because their school life has been disrupted.
"There is also the real possibility that some of these children will suffer physical and emotional harm, particularly if they are taken off the school roll and their whereabouts become unknown. Recent high-profile cases of child sexual exploitation have involved children missing from education, and there is also a correlation between missing education and becoming a victim of forced marriage."
Dr Emery added: " We are calling on government to conduct a national review of children missing education, to improve the way data is collected both locally and nationally. The review should consider how local authorities, schools, social services and their partners can work with children and their families, to ensure they and their families receive the best support possible so they can get back into education."
A Department for Education spokesman said: "These findings are misleading and unhelpful.
"Missing education is defined as a child not being registered at school when they should be or not being otherwise educated. This report inappropriately includes children who have missed one or two days of school, for anything from moving between schools to being sent home for having behavioural problems.
"The report wrongly assumes that these children are all automatically vulnerable or have slipped off the radar.
"Local authorities and schools are best placed to keep accurate records of children in education and our recently-revised guidance makes clear there is no excuse for them not to meet their responsibilities in this area. Parents have a legal responsibility to ensure their children are receiving a proper education."