These colleges are often portrayed as elitist "super grammar school sixth-forms", says the report from the Learning and Skills Development Agency.
But this stereotype can be misleading, the report suggests. "The trend towards enrolling students who, 10 years ago, might not have continued education beyond the age of 16 is continuing and growing," says the report. It adds that the majority of sixth-form colleges are performing well and providing excellent "added value".
"In other words, some colleges with an intake of low-ability students achieve substantial progress with these students, although the final results may not seem particularly impressive," the report says. "On the other hand, some colleges that achieve better results display value-added performances significantly below the average."
Those colleges with deprived student profiles tended to be conscious of the potential conflict between an open entry enrolment policy and the drive to raise student achievement. They were also anxious about the public perception of college performance tables if entry requirements were lowered. "Yet the research shows that , in the majority of sixth-form colleges, students from deprived neighbourhoods are achieving improvements as good as those from less deprived neighbourhoods," the report concludes.
The best sixth-form colleges are characterised by the quality of their informal, internal communication as well as their good staff and student morale.
The study also finds that improvements made by students from entry to completion is often different from their raw results in terms of A-level passes.
'Rising to the challenge: widening participation and raising achievement in sixth-form colleges' is available free from the LSDA. Telephone 020 7297 9144