The DISS project is the largest study of teaching assistants and other school support staff carried out in the world. The research was conducted between 2003 and 2009.

It is the first longitudinal study to analyse the impact of TAs on teachers, teaching and pupils' learning, behaviour and academic progress in everyday classroom settings. The findings have been widely reported in the media and have important implications for teaching, school management and the education of pupils - especially those with special educational needs.

Contrary to commonsense views about TA support (i.e. more adult support for those who need it most helps them to progress), we found that a negative relationship between the amount of TA support received and the progress made by pupils in mainstream primary and secondary schools. These results were not attributable to pupil characteristics, such as their prior attainment or SEN status, and nor could we explain them in terms of decisions made by TAs. Instead, it is the way schools and teachers deploy and prepare TAs – factors that are out of TAs’ control – that best explain the surprising results.

The DISS project findings are detailed in our book Reassessing the Impact of Teaching Assistants. In it we reveal the extent to which pupils in most need are let down by current arrangements and present a robust challenge to the widespread practices concerning TA preparation, deployment and how they interact with pupils. Links to our key publications based on the DISS project are posted in the right sidebar.