Teaching assistants (TAs) are crucial to the work of schools and colleges across England. Their contributions are invaluable, particularly for those pupils most in need of additional support. The TA role is broad, changeable and context specific. Duties can include supporting pupils' readiness for learning, access to learning and recap of learning; assisting teachers in resourcing and delivering lessons; working in conjunction with families for pupils with special educational needs and disabilities (SEND); and leading interventions. This guidance report focuses on the deployment of TAs in mainstream primary and secondary schools. While the recommendations may also be applicable in special schools, alternative provision, early years settings, and colleges, it is likely that they will need to be interpreted differently to suit these contexts. The recommendations are drawn from the evidence base on TA deployment practices and how these can lead to improved pupil outcomes. This is an update to a previous guidance report on the deployment of teaching assistants. While many of the key messages remain the same, the updated recommendations have been created from a new review of the evidence and in consultation with an expert advisory panel. This report draws from a review of the evidence on TAs from the EEF's Teaching and Learning Toolkit. This looks at 52 studies identified from a systematic review, guided by research questions based on the following themes: how leaders can manage and support TAs, how teachers and TAs can work to support pupils (including pupils with SEND), and which practices are effective in supporting these pupils. Additional evidence sources were considered including a previously commissioned 'SEND in Mainstream Schools' evidence review. Further details of these can be found in the evidence to decision framework which sits alongside this report. Where appropriate, this report also draws on evidence from the wider suite of EEF evidence reviews. Insights into current practice have been drawn from a range of available recent research and from the input of the guidance panel. A full list of references can be found at the end of this report and in the evidence to decision framework.