An increasing number of classroom assistants (also called teaching assistants and sometimes learning support assistants) are employed in schools throughout the UK, but their impact appears variable. This paper presents an evaluation of a local authority project which placed five additional classroom assistants (CAs) in three primary schools in disadvantaged areas for nine months, with the aims of improving the quality of learning in the classroom, having a positive impact on the personal and social development of pupils, and encouraging parental involvement in their children's learning. The results suggest that the project's aims were met; the data also highlighted ways in which the CAs' impact could be enhanced when deployed in schools in the future (for instance, better contact with parents, greater liaison with the class teacher). Suggestions for future research are given.