The first findings from the Open University-led "back on course" programme - which has analysed data on almost 15,000 "early leavers" - suggest that 47 per cent come from the most advantaged two-fifths of the population.
It follows results from the first two years of the project, which has offered independent advice and guidance to thousands of students in England who left higher education early.
Although its success in building up a bank of knowledge and expertise has led almost 100 universities to join the programme, its funding is due to run out in July 2012.
Through its partnership with the Universities and Colleges Admissions Service, the programme looked at the records of 14,730 students from 42 participating universities.
It found that although coming from a disadvantaged neighbourhood or having few formal qualifications meant a student was more likely to leave early, those factors did not play a disproportionate role, as previous research has suggested.
"People have tended to imply that people who leave early are those with low (Ucas) tariff points and those from low-participation backgrounds," said Barbara Stephens, the project director. "One of the things that this says quite clearly is that almost any student could leave - it is the reasons why they do it that might vary."
The research found, in particular, that students with good A levels or affluent families were much more likely to cite problems with their course or institution as opposed to personal reasons for leaving.
"I think that is quite stark. It may be the schools that are making assumptions about what is best for people with high [Ucas] tariff points," Ms Stephens said.
By comparing its data with the student cohort at the same institutions, the research also found that students who were male, white or who had applied from further education were more likely to drop out.
Those studying very close to their family home were also at greater risk - 47 per cent of dropouts were at universities within 25 miles of home.
Ms Stephens said she had been struck by the lack of "connection" that such early leavers - who often quit without telling anyone - had formed with their institution.
While institutions themselves were not to blame, she said, they should "not be let off the hook", with such aspects as first-year inductions being of crucial importance.
She also welcomed Ucas' admissions process review, given that course selection made through the "panic" of clearing was a factor in many students' decisions to leave.
The programme now faces a financial challenge. With money from the funding council due to run out within months, it must seek contributions from universities.
If it fails to secure such funding, it could go the same way as another nationally coordinated scheme to aid wider participation - Aimhigher - and close.
"The amount it would cost any one institution to try to trace their early leavers, contact them and then deliver this sort of information, advice and guidance - it is just not economical," Ms Stephens said.