At a time when children and young people’s involvement in research is increasingly the norm, this article reflects on the importance of a well-reasoned and transparent justification for their inclusion or exclusion. It explores the dilemma of a researcher’s ethical obligation to protect children and young people from harm and at the same time respect their autonomy as social actors and independent rights holders to participate in research of relevance to their lives. A researcher’s ethical obligation to conduct a rigorous but balanced assessment of harm and benefit is reiterated. The article takes the debate beyond a call for assessing harm and benefit to providing a strategy for conducting such an assessment at the point of research design. Reflecting on two research projects the authors were involved in, three critical considerations are identified. These are: the purpose and the theoretical context of the research; the preferences of the children and young people and their parents; and the available time and resources. The article draws on the research examples to illustrate the assessment process in practice.