Studies carried out by the Further Education Development Agency show students who gave up put the attitudes and teaching of college staff high on the list of factors affecting their decision.
Researchers found it difficult, however, to identify classic reasons such as financial hardship and social factors as significant indicators of drop-out rates.
The agency research indicates that colleges can do much to increase staying-on rates by altering what they do. Previous research has suggested that drop-out rates are largely outside colleges' control.
The study, by Dr Paul Martinez, focuses on three colleges, one on the Isle of Wight, and two in London. In each case researchers interviewed large numbers of students as they started college and when they dropped out. Academics were trying to find factors which might mark out students likely to drop out.
But in all three cases social factors could not distinguish those who eventually dropped out from those who completed their courses.
Dr Martinez said in a report: "Difficult personal and financial circumstances clearly play a role, but on their own they do not readily distinguish withdrawn from current students. Some of the most important causes of non-completion relate directly to the core activities of colleges and to the student experience of college."
In the case of both London colleges, factors identified as important by those who left their courses early emphasised teaching quality, help with course work, timing of courses and the support given to students.
However, Dr Martinez said the agency's research had contradicted much British and American research - pointing to the need for further study.
Conclusions of the Further Education Development Agency research, are significant, however, given efforts to put staying-on rates at the top of the further education agenda.
Barrister Helena Kennedy, in her report on widening participation in further education, argued strongly that keeping students on courses was as important as attracting them to college in the first place.
Maintaining staying-on rates are also a key part of Government plans for the Welfare to Work scheme, prompting ministers to build careers advice into the scheme to encourage people to stay on courses and persevere with subsidised jobs.