Background: Emotional distress has received less attention as an explanatory factor for self-injury in people with intellectual disabilities, with research and practice primarily focusing on biobehavioural factors. This systematic review examines the self-reported explanations for self-injury by people with mild or moderate intellectual disabilities, and discusses how the findings contrast with those from self-reported studies of people within the general population who self-harm. Methods: Five databases (PsychINFO, IBSS, CINAHL, Web of Science and Medline) were systematically searched to find qualitative, empirical research since 2000 about self-reported reasons for self-injury. Results: Four studies were found which conducted research with people with intellectual disabilities. Three primary themes are discussed: relief from overwhelming emotions; trauma and loss; and difficulty in articulating emotions. Conclusion: This review found a paucity of research asking people with intellectual disabilities about their own self-injury. However, the research available suggests that explanatory factors for self-injury typically reported in the general population should be considered for those with mild or moderate intellectual disabilities.