University summer schools, designed to encourage applications from poorer youngsters, make a significant impact, suggests research.
Among students who attended summer schools run by the Sutton Trust, 76% gained places at leading universities, according to a report from the education charity.
The figure for students not attending the summer schools was 55%.
Researchers said the findings suggested that "summer schools do work".
Since 1997 the Sutton Trust charity, which works to improve educational opportunities for disadvantaged youngsters, has provided funds for 10,000 bright pupils from poor backgrounds to attend summer schools at leading universities, including Oxford, Cambridge, Bristol and Nottingham.
The idea is to give 17- and 18-year-old pupils, who might later become the first in their families to go on to higher education, a taste of university life.
They attend lectures in their chosen subjects and are mentored by student volunteers.
In order to apply, the pupils must have five top GCSEs and meet a series of measures of an underprivileged educational background, for example attending a poorly performing school.
The summer schools are regularly oversubscribed by a factor of seven to one.
The research, led by Dr Tony Hoare and Rosanna Munn at University of Bristol, attempted to quantify the effectiveness of the scheme.
"I was pleased with the results. The word on the street from the universities was that summer schools worked, but until now the evidence was anecdotal," said Dr Hoare.
The team measured the effectiveness of the scheme, including tracking up to 250,000 students through the Ucas university application system.
The researchers found strong statistical evidence that having attended a summer school was associated with an increased likelihood of applying to at least one of the participating universities and to other leading universities.
"Not only does the summer school experience encourage all attendees to target the more elite universities, but what is particularly encouraging is that they reduce, sometimes to vanishing point, the greater reluctance of the more underprivileged groups to do so," the authors conclude.
This year the Sutton Trust will hold summer schools in 50 subjects at seven universities: Cambridge, St Andrews, Bristol, Nottingham, Durham, University College London and Imperial College London. Oxford now runs its own scheme.
The summer schools are one of a number of outreach initiatives aimed at encouraging young people from poorer backgrounds to apply to university.
The schemes include bursaries and visits, and are funded not only by the educational institutions themselves but by businesses, government and charities.