Placing children with learning or behavioural difficulties in mainstream classes does not drag down the education of other pupils, according to a government-funded study.
The Manchester university report concludes that schools have no reason to fear that the Government's "inclusion agenda" is damaging standards.
The researchers looked in depth at 26 studies on the impact of including pupils with special needs in mainstream education, mostly carried out in primary schools in the United States.
These reports produced 40 findings. Of these, 21 showed that inclusion had made no difference to other pupils, nine that it had a positive academic or social impact, six a negative impact and four a mixed effect.
The researchers warned inclusion only had positive effects if schools received proper support.
"Successful inclusion doesn't occur in a vacuum," the report said.
"Parents, teachers and pupils need to be fully committed to the idea, programmes of work have to be carefully planned and reviewed regularly and support staff need to receive appropriate support and training."
Chris Keates, general secretary of the NASUWT, Britain's second largest teaching union, said: "We have never been opposed to inclusion when children with special needs have been given the support they need. "The problems come when that support is not there, and teachers use up their time and expertise helping a single child leaving the rest of the class to their own devices."
The impact of population inclusivity in schools on student outcomes is at http:eppi.ioe.ac.uk