Single-sex school classes could help overcome a "laddish" culture that stops boys from learning, a study shows.
The Cambridge University research found that separating children for some subjects helped boys to concentrate and improved their exam grades.
Girls consistently score better than boys in school examinations.
The Department for Education commissioned the four-year project involving 50 schools in an attempt to close the gap.
Led by Mike Younger and Molly Warrington, the researchers said: "Many girls and boys feel more at ease in such classes, feel more able to interact with learning and to show real interest without inhibition, and often achieve more highly as a result."
Some single-sex classes have developed problems, however, as groups of boys set up a "macho regime" which alienated others in the class.
But overall, the academics concluded: "Evidence in favour of the development of single-sex classes for some subjects, from both students' voices and from an analysis of levels of academic achievement, is nonetheless persuasive."
Last year, David Miliband, who was schools minister at the time, backed the idea of single-sex classes. But ministers have not publicised the concept since.
A spokesman for the Education Department said a range of policies including "reading champions" were already in place to address the gender gap.
He said: "We consider that it is a matter for individual schools to determine which strategies are most appropriate for their particular circumstances and to address their pupils' specific needs."