Thousands of budding teachers never make it into the classroom, according to new research.
Many fail to finish training courses, while others struggle to find teaching jobs, it was suggested.
The Good Teacher Training Guide 2012 also reveals that high numbers of maths, science and languages teachers do not have good degrees in their subject.
Researchers at Buckingham University's Centre for Education and Employment Research analysed official data on teacher training for the 2010/11 academic year, looking at where trainees study, the numbers entering the profession and the types of qualifications they hold.
The findings show that in 2010/11, 70.4% of 37,734 teacher trainees were in teaching posts the following January.
This means that around 11,000 did not enter the profession.
Of those that did become teachers, 60.6% went to work in state schools, 4.9% found jobs in private schools and 4.9% were in teaching, although the sector was unknown.
Report author Professor Alan Smithers said that for the year examined, teacher training was a two-stage process with individuals doing their training and then looking for a job.
"Some people start with teacher training and it becomes clear to them that they are not going to make good teachers, and others successfully complete and they're not necessarily able to find a job," he said.
Ministers have announced plans to overhaul teacher training, moving it away from universities into schools.