Background: Social support is a protective factor for siblings of children with neurodevelopmental disorders.Aims: We reviewed studies on social support received by siblings of children with neuro-developmental disorders.Methods and procedures: We conducted a pre-registered systematic review (CRD42020207686), searching PsycINFO, MEDLINE, Web of Science, and Scopus.Outcomes and results: Fifteen articles were eligible for the review, 13 of which used cross-sectional designs. Two studies investigated sibling social support after an intervention. Multiple variables were negatively related to social support (e.g., sibling depression, loneliness, stress). Variables that were positively related to social support included prosocial behavior, competence (academic, social, and activity-related), problem-focused coping, and family quality of life. Potential mod-erators of the relationship between social support and psychosocial adjustment included the type of disorder of the affected sibling and the type of social support provider. We conclude with an overview of the reliability and validity of the seven social support measurements used across the studies.Conclusions and implications: Lower levels of social support are associated with more negative psychosocial adjustment among siblings of children with neurodevelopmental disorders. We encourage future researchers to further investigate ways to increase social support for siblings to improve outcomes.