Barnardo's calls for fairer school admissions
Schools should be required to take equal shares of pupils in different ability groups to help poorer students succeed, a children's charity says.
Barnardo's claims its proposal, known as "fair-banding", could reduce social segregation in the school system.
Fewer pupils from poor homes get into England's top schools - partly because their parents are less able to navigate the admission system, Barnardo's says.
The government plans to direct extra funds to schools taking poor pupils.
This will be by way of a "pupil premium", but no details of how much extra will be available have been given.
Education Secretary Michael Gove says England has an "unbelievably complicated" school admissions system.
He told BBC News a fair banding system "had a role to play" and was used in some very good schools.
But he added: "In England, we have one of the most unequal education systems in the developed world. Admissions is just a part of it and I would not like to over-state it."
It has long been argued that middle-class parents are more able to play the admissions system than those from poorer backgrounds.
The Barnardo's report says "middle-class parents tend to be strongly engaged to get the best result from the admissions process - even to the extent of moving house".
Disadvantaged parents are less likely to exercise their right to choose and more likely to simply opt for their local school, it adds.
This may be because they are daunted by the system or because education is not a priority for them.
This leaves children from poorer homes attending poorer schools, and leads to "educational disadvantage being passed down from one generation to the next", the report says.
Martin Narey, chief executive of Barnardos, told the BBC: "We expect education to be the great leveller, we expect education to give all children an equal chance of doing well.
"Half of all free school meal children are in just a quarter of our schools. Children from poor backgrounds are squeezed out of good schools.
But Dr David Green, director of think tank Civitas, told the BBC: "This approach is, to my mind, a kind of social engineering based on animosity to middle-class parents.
"You need to leave schools free to choose their own curriculum to target remedial measures."
The Barnado's study cites research which shows that children from poorer families are half as likely to get five good GCSE grades as their richer classmates.
Studies have shown that children who are put into a class with high-achieving peers are likely to see their own results improve.
The report adds that there is clear evidence that many schools which control their own admissions, such as faith schools, are more socially selective than those that do not.
And it says action is needed in the light of the planned expansion of such schools in the form of academies and free schools.
These will be outside of local authority control and will manage their own admissions.
The Department for Education points out that academies and free schools, like all schools, will have to follow the admissions code which seeks to ensure the system by which children are admitted is fair.
And it says that academies take a higher proportion of children on free school meals than the national average.
But this is partly because under the Labour government they were set up in areas of extreme social disadvantage.
The coalition government's new-style academies will be selected from England's top-performing schools, rated outstanding by Ofsted.
These will be fast-tracked to academy status, with some opening this September.
Report author Anne Pinney says she is concerned about moves to extend school freedoms, which include giving those schools control over their admissions policies.
Her report calls for schools, especially those in urban areas with high levels of social segregation, to promote fair banding as a fairer basis for admissions.
Under this system, pupils would take a standard test and would then be divided into five ability bands based on the results.
Schools would then admit pupils in equal proportions from each ability band.
The report calls for schools to report back to parents and governors on their intake and to include the percentage of pupils they take who qualify for free school meals.
It also argues that, when schools set their own admissions code, decisions on who to admit should be done by a body independent of the school.
The report also urges independent scrutiny of school admissions practice, perhaps by Ofsted, with official recognition for particularly good practice.
A Department for Education spokesman said: "The attainment gap in English schools is too wide and far too many students from disadvantaged backgrounds are in weaker schools.
"That is why we are implementing a comprehensive programme to make opportunity more equal.
"We are introducing a pupil premium; reforming the admissions system to make it simpler and fairer and getting the best teachers in the most disadvantaged areas."
Sue Berelowitz, deputy children's commissioner for England, said: "As Barnardo's point out, the top secondary schools on average only take 5% of pupils entitled to free school meals, so a level playing field is needed.
"All the available evidence shows that in order to narrow the achievement gap children from disadvantaged backgrounds should have equal access to the best schools."