Support staff need more training in science and numeracy if pupils are to benefit fully from their go-between role, according to a review by the London Institute of Education's evidence for policy and practice information and co-ordinating centre.
The study said that teachers also need more training to ensure they make the best use of assistants in class.
The review of more than 10,000 studies carried out worldwide since 1988 examines the views of teachers, heads, assistants, parents and pupils.
It contradicts findings of a study carried out by Professor David Reynolds, a former government adviser, published in 2004, which said assistants had failed to raise classroom standards.
Support staff made direct contributions to pupils' academic achievement and helped ensure all children were included in classroom activities. They also acted as a link between the school and parents and helped support teachers by performing routine tasks, the new report found.
It said: "Teaching can no longer be seen as a one-person enterprise. Our findings suggest that support staff are taking an increasingly important role in supporting learning."
Teacher training should prepare trainees to work with others and to incorporate the work of assistants into lesson planning.
The review found some teachers fail to do this or restricted the role of the assistants to managing difficult children.
Children who work closely with assistants can become dependent upon them if assistants do not recognise the problem and realise when they need to withdraw support.
* Working with adults: A systematic literature review on the perceptions of ways in which support staff work to support pupils' social and academic engagement in primary classrooms (1988-2003) is available from http:eppi.ioe.ac.ukEPPIWebhome.aspx?page=reelreview_groupstta_adults review_one.htm