It is increasingly common for pupils with Down's syndrome to be offered places in mainstream primary schools. However, there is still much to learn about the impact of these placements upon children and classrooms. Recently the Nuffield Foundation funded a two-year research project exploring the inclusion of primary-aged pupils with Down's syndrome. The research focused on the inclusion of 18 pupils with Down's syndrome who attended mainstream primary schools in six local education authorities (LEAs) in the north-west of England. The research team investigated the ways in which schools manage the inclusion of pupils with Down's syndrome and the factors that contribute to the success of mainstream placements. In this article, Sam Fox, Peter Farrell and Pauline Davis from the University of Manchester discuss some of the findings from the study. These concern the support in place for the child and the attitudes of staff, other pupils and the parents of peers towards the inclusion of the child with Down's syndrome. Evidence from the 18 case studies suggests that there is no single way to guarantee effective inclusion. The extent to which a child is effectively included in a mainstream class is likely to be influenced by a number of key factors, including the way in which the teaching assistant (TA) works with the class teacher. Inclusion is more likely to be successful when the class teacher takes a central role in the management of support and the organisation of a child's daily educational experiences.