The study - which was commissioned to see how to make best use of the new Pupil Premium (a new extra funding scheme for poorer students) - claims many of the methods schools put in place to improve performance have little effect.
School uniforms, smaller classes and homework were all criticised as having little impact in the report by The Sutton Trust, whilst classroom assistants had only a 'very small or no effect' on attainment.
The report conceded that assistants can have a 'positive effect' on pupils' attitudes to work, but their presence can negatively impact on standards when used as a replacement for teachers.
The numbers of teaching assistants in schools rose dramatically under Labour, and their popularity has continued with around 214,000 hired so far this year.
What do you think?
Does your child benefit from having a teaching assistant in the classroom?
Are you a teaching assistant?