Chapter 7 addresses key global and local (macro and micro) ethical dilemmas when working with children, particularly when they are in active roles. It outlines generic ethical issues relevant to research with under-18s and addresses ethical issues when moving from research ‘on’ and ‘about’ to research ‘with’ and ‘by’ children. As well as addressing the origins and main dilemmas of child-focussed ethics, the chapter evaluates several existing international ethics guidelines for research involving child participants that are potentially relevant for applied linguistics, drawing out challenges, opportunities and tensions. It revisits the key messages of the UN Convention on the Rights of the Child as a point of reference for ethical research practice, addresses the process of securing child consent or assent and discusses good practice when securing permissions from other stakeholders. Ethical issues, specifically when working with multilingual children and families, are covered as well as how ethical guidelines must be sensitive to cultural, social and contextual circumstances, making reference to issues in different contexts, including those in the Global South.