In recent years there has been an unprecedented increase in support staff in schools in England and Wales. There were widespread expectations that this will be of benefit to teachers and pupils but there has been little systematic research to address the impact of support staff. This study used a naturalistic longitudinal design to investigate the relationship between the amount of support (measured by teacher estimates and systematic observation) and pupils' "Positive Approaches to Learning" (PAL) and academic progress. There were over 8000 pupils across two cohorts and seven age groups. Results on PAL were not straightforward by there was a consistent trend for those with most support to make less academic progress than similar pupils with less support, and this was not explained by characteristics of the pupils such as prior attainment or level of special educational need. (Contains 6 tables and 1 note.)