The purpose of this systematic review was to investigate the learning, social, and psychological outcomes of students with moderate, severe, and complex disabilities (MSCD) in inclusive settings. The review discusses barriers to conducting rigorous research in this field. Whilst an initial literature search located 1,338 records, only 18 were finally included due to the eligibility criteria. Studies were placed in categories based on the topics investigated. Regarding learning outcomes of students with MSCD, findings were moderately in favour of school inclusion for both academic achievement and adaptive skills. Regarding social outcomes, results showed that inclusive settings offer more access to instructional time and peer interaction, although they reported marginalisation during class activities and social isolation within the peer group. Finally, in terms of psychological outcomes, inclusive settings appeared to reduce the frequency of challenging behaviours. The paper also addresses conceptual barriers regarding the definition of inclusion and its consequences on research and practice as well as research design barriers resulting from the quality of research in this field. Based on review results, this paper outlines epistemological propositions for developing standards of quality for both research and practice in the field.