Almost 10,000 budding teachers were not in the classroom six months after leaving training courses in 2012, according to new research.
More than one in 10 of those in their final year of training failed to pass or meet the requirements to become a qualified teacher, it found.
The latest Good Teacher Training Guide also reveals that would-be teachers who train in schools are more likely to take up teaching posts than those who train on university courses.
But university-led teacher training is more likely to attract applicants with good degrees.
The findings come as the Government attempts to overhaul teacher training, moving it away from universities and into schools.
Researchers at Buckingham University's Centre for Education and Employment Research analysed official figures on teacher training for the 2011/12 academic year, looking at where trainees study, the numbers entering the profession and the types of qualifications they hold.
They reveal that of the 36,898 people in their final year of training in 2011/12, around one in four (25.3%) - about 9,328 individuals - were not in teaching the following January (six months later).
Around 3,927 (10.6%) of these never achieved Qualified Teacher Status (QTS) while the others were simply recorded as not being in teaching posts.
"Together they amount to a quarter of the recruits not making it into the classroom, at least straightaway," the report says.
It adds that this seems like a "wasteful loss", but adds that it is 5.2 percentage points lower than the proportion that were not in teaching at the same point the year before.
A breakdown of the figures shows that 80.9% of those who-trained on programmes led by schools entered teaching, compared to three-quarters (76.1%) of those on university-led courses.
Under teacher training reforms, ministers have also been trying to attract more top graduates - those with at least a 2.1 degree - into the profession.
New bursaries, worth up to £25,000 in some subjects from this September, are being introduced for those with at least this standard of degree.
The latest research shows that would-be teachers in subjects such as history and English are still more likely to have a good degree than those training to teach maths or science.
It found that 83% of history trainees had a first or 2.1, along with 78% of English trainees and 87.8% of classics trainees.
The least well-qualified are information and communication technology (ICT) trainees, with just over half (53.6%) holding a 2.1 or better, along with 54.8% of those planning to teach science, 55% of design and technology trainees and 60.5% of would-be maths teachers.
These are the areas "where arguably subject expertise as measured by degree class is especially important", the report says.
It adds that overall, university-led training schemes had the most highly qualified entrants, although their students were less likely to take up teaching posts than those who trained on employment-based initial teacher training schemes (EBITTS) or on school-centred initial teacher training schemes (SCITTS).
It adds that overall, the percentage of recruits with good degrees has risen year by year.
The researchers conclude that both university-led and school-led training schemes have their strengths.
"University-led programmes tend to have entrants with higher entry qualifications and better Ofsted grades, but school-led programmes tend to have higher teaching take up and to be rated more favourably by newly qualified teachers," the report says.
Report author Professor Alan Smithers said: "It is a strong plus for school-led approaches that more of the trainees become teachers.
"The point of teacher training, after all, is to train teachers. Trainees also favour this route.
"But three-quarters of teachers currently come through the universities so the Government must be careful not to turn off the tap too quickly.
"There are already major shortfalls of maths, physics, ICT and modern languages teachers, which school-led programmes show no sign of ameliorating."
The Government introduced a new initiative in autumn 2012 called School Direct which it says gives schools the opportunity to recruit and train staff.