Some schools are using extra funding designed to help their poorest pupils to boost the results of all youngsters, or to plug holes in their budgets, a poll of teachers suggests.
A new survey reveals that just over half of teachers (53%) say their school is using pupil premium funding to raise the attainment of disadvantaged children.
But around one in six say the funds are being used to improve all pupils' results while others are using the money to pay for activities affected by budget cuts (7%).
The pupil premium is extra cash designed to help schools boost the achievement of disadvantaged youngsters.
From this September, the premium will be worth £1,300 for each eligible primary school pupil and £935 for each eligible secondary school pupil.
The new survey, commissioned by the Sutton Trust, also reveals that just over a fifth (22%) of teachers say their school is using the funding to help pupils who are falling behind in class.
Sutton Trust chair Sir Peter Lampl said: "The pupil premium was established to break the cycle of disadvantage that begins when poor children underachieve at school. It's vital that the funds to help these pupils are well-targeted and used in a cost-effective way."
:: The poll of 1,163 teachers was conducted by the National Foundation for Educational Research.
A Department for Education spokesman said: "Headteachers are free to use their professional expertise to spend the pupil premium in the way they think will most benefit disadvantaged pupils.
"This poll shows that the vast majority of teachers believe their school is spending the pupil premium directly on disadvantaged children, while the remainder is spent on benefiting all pupils, for instance improving the quality of teaching. Evidence shows that the pupils who benefit most from this kind of whole-school improvement are disadvantaged pupils."