Purpose: The purpose of this paper is to explore ways in which children and young people are being positioned as change agents for families through school health promotion initiatives in New Zealand. Design/methodology/approach: The paper maps and describes the kinds of policies and initiatives that directly or indirectly regard children as conduits of healthy eating and exercise messages/practices for families. Drawing on post-structural theoretical frameworks, it explores what these resources suggest in terms of how healthy families should live. Findings: Families are positioned as central to school health promotion initiatives in New Zealand, especially in relation to obesity prevention policies and strategies. Children are further positioned as agents of change for families in many of the resources/policies/initiatives reviewed. They are represented as key transmitters and translators of school-based health knowledge and as capable of, and responsible for, helping their families eat well and exercise more. Social implications: While recognising children's agency and capacity to translate health messages is a powerful and welcome message at one level, the author need to consider the implications of requiring children to convey health information, to judge their family practices and, at times, to be expected to change these. This may create anxiety, family division and expect too much of children. Originality/value: The paper takes a novel post-structural perspective on a familiar health promotion issue. Given the proliferation of family-focussed health initiatives in New Zealand and elsewhere, this perspective may help us to explore, critique and understand more fully how children are expected to be engaged in these initiatives, and the potentially harmful implications of these expectations.