This thesis concerns the social status of 8–12 year old children with moderate learning difficulties (MLD) who are integrated into mainstream schools. The terms 'MLD', 'integrated' and 'social status' were first defined. Methods for assessing children's social status in school were then reviewed. A new sociometric assessment method was designed and was compared in Study 1 to a range of other commonly used sociometric classification methods. The literature on the social status of integrated MLD children was reviewed and in Study 2 the new sociometric assessment method was used to assess the social status of a sample of 118 integrated MLD children and their 1100 classmates. MLD children were found to be less socially accepted and more socially rejected than their classroom peers. Study 3 investigated personal and environmental variables hypothesised, on the basis of theoretical models and findings from studies with mainstream children, to be associated with the social status of a sample of 115 integrated MLD children. Both personal and environmental variables were found to contribute significantly in discriminating between the sociometric status groups of MLD children. Concepts from social exchange theory were found to be useful in interpreting the findings. Comparison of the 115 MLD children with 867 mainstream classmates on behavioural variables found different variables to be associated with Popular and Rejected status in each sample. Further analyses of subgroups of rejected children, identified through cluster analysis, supported the conclusion that important differences exist between mainstream and MLD children. Differences were also found in the stability of rejected MLD and mainstream groups from analysis of a cohort of 416 pupils who were followed longitudinally over the two years between Studies 2 and 3. Finally Chapter 10 discusses the contributions and limitations of the thesis, drawing out implications for research and practice.