Bright poor boys are around two-and-a-half years behind their rich, clever male classmates in reading, a study has suggested.
It reveals that high-achieving boys from disadvantaged backgrounds are more likely to perform poorly on international tests than those in other nations.
The report, commissioned by the Sutton Trust, warns that action must be taken to ensure that schools are supporting bright students so they do not lose out on top university places and good jobs.
The study analysed the 2009 scores of 15-year-olds taking part in the Organisation for Economic Co-operation and Development (OECD) international PISA reading tests.
It found that bright English boys from the poorest families lagged 30 months - two-and-a-half years - behind their high-achieving male classmates from the richest backgrounds.
This gap was bigger in England than in every other developed nation apart from Scotland.
In countries such as Canada, Denmark, Germany and Finland, this gap was 15 months or less, the study found.
It added that among clever girls, the reading gap between those from the richest and poorest homes was two years and four months.
The researchers also looked at the gap in reading skills between children of all abilities.
The findings showed that in general, the poorest teenagers in England lagged two years and four months behind their richest classmates in reading.
This put England 23rd out of 32 countries who took part in the tests, ahead of countries including the USA and France, but behind others including Norway, Chile and Slovenia.
Sutton Trust chairman Sir Peter Lampl said the gap in boys' achievement was a "worrying issue".
"This matters for two important reasons," he said.
"First, it is clearly economically inefficient not to tap into talent wherever it exists.
"By not stretching our most able students from all backgrounds, we are not only failing them, we are reducing our ability to compete globally.
"Second, such under-achievement perpetuates those inequalities which make it so hard for bright children to move up in society."
The study, by Dr John Jerrim of the Institute of Education, comes weeks after Ofsted warned that tens of thousands of clever children were being let down by England's state secondary schools.
A culture of low expectations in many schools meant that bright pupils were not being stretched and were failing to gain top grades at GCSE, according to a report published by the inspectorate.
Chief inspector Sir Michael Wilshaw said it was "shocking" that, in some cases, school leaders and teachers did not even know who their most able children were.
The Sutton Trust is calling on the government to introduce a programme that identifies children with high potential when they start school to ensure that they are supported throughout their education.
It also suggested that a new measure looking at the progress made by the top 10% of pupils in each secondary school be included in annual league tables.
Sir Peter said: "We need to improve the support given to highly able children in comprehensive schools and academies.
"That is why it is so important that there is a targeted scheme that ensures that those with high potential from low and middle income backgrounds are identified and helped to thrive.
"Parents and students need to know that highly able young people will be given the backing they need to succeed regardless of which school they attend."