In this article, we explore the ethical issues related to the reporting of suspected abuse or neglect in research involving children. Ethical dilemmas related to reporting child maltreatment are often complex because the rights of children and their adult caregivers may conflict and determinations of abuse or neglect are socially constructed judgments that depend on particular circumstances. We argue that when reporting is legally mandated, investigators must follow the law and report their suspicions to Child Protective Services. When reporting is not legally mandated, investigators still have an ethical obligation to report to help prevent additional maltreatment and allow children to obtain access to services needed to recover from abuse or neglect. We also argue that investigators should include plans and procedures in the research protocol for making reports and training research staff in recognising evidence of child abuse or neglect. Although investigators should report evidence of abuse or neglect that is discovered incidentally, they have no mandate to actively search for such evidence when it is not related to the study’s objectives. Investigators should also inform parents and children about their obligations to report suspected abuse or neglect.