Research has suggested that autistic young people have an increased risk of self-harm. In non-autistic people, self-harm typically emerges in adolescence and is associated with deleterious long-term mental health outcomes. However, existing literature on self-harm in autistic young people (aged 10–24 years old) is limited. This entry aims to provide an overview of the current knowledge on self-harm in autistic young people. It identifies gaps in the literature and makes recommendations for future research by presenting existing studies on self-harm in autistic young people in terms of prevalence, development and maintenance, and risk and protective factors. This entry highlights that although previous research has investigated self-harm in autistic young people, substantial gaps in knowledge still exist. Future research on this topic will need to address several methodological issues, particularly how to: (i) define and measure self-harm in autistic young people, (ii) produce findings that increase our understanding of self-harm and account for heterogeneity in the autistic population, and (iii) use longitudinal methods to identify risk and protective factors for self-harm in autistic young people. We explore how future research can address these challenges and inform the development of effective, evidence-based prevention and intervention strategies to support the mental health and well-being of autistic young people.