It discusses the different mechanisms through which learning support staff can have an impact on teachers’ work and student achievement and reviews the related empirical evidence. While the available research provides mixed evidence on the impact of learning support staff on student achievement, it suggests that learning support staff may improve teaching and learning as long as adequate strategies for their training, deployment and use are implemented. There are several ways through which learning support staff may have a positive impact on student attainment. Students receive more individualised help and attention from either the support staff or the teacher, and the learning environment can be made more flexible possibly leading to increased engagement and inclusion of children in classroom activities.