Background: Children without disabilities in out-of-home care have a higher risk of child sexual abuse [CSA (Euser et al. 2013)]. In this study, we examined the year prevalence of CSA in out-of-home care for children with a mild intellectual disability, and compared it with the prevalence in out-of-home care for non-disabled children and children in the general population. Materials and Methods: Professionals (N = 104) from out-of-home care facilities reported cases of CSA that occurred in 2010 for the children they worked with (N = 1,650). Results: In out-of-home care for children with a mild intellectual disability, 9.8 per 1,000 children were victims of CSA. This prevalence was significantly higher than in regular out-of-home care and in the general population. Conclusion: Children with a mild intellectual disability in out-of-home care have an increased risk of CSA. Adequate education and support for both children and caregivers is necessary to recognize and prevent further sexual abuse.