Harm reduction has become increasingly influential in drug policy and practice, but has developed primarily around adult drug use. Theoretical, practical, ethical and legal issues pertaining to children and adolescents under the age of majority - both relating to their own use and the effects of drug use among parents or within the family - are less clear. This commentary proposes a sub-field of drug policy at the intersection of harm reduction and childhood which we refer to as 'child-centred harm reduction'. We provide a definition and conceptual model, as well as illustrative questions that emerge through a child-centred harm reduction lens. Many people in different countries are already working on these kinds of issues, whose work needs greater recognition, analysis and support. In beginning to name and define this sub-field we hope to improve this situation, and inspire further international debate, collaboration, and innovation.