An increasing focus has been placed on schools as suitable settings for promoting pupils’ wellbeing. High levels of wellbeing are associated with flourishing, where children enjoy life and better overcome challenges. A substantial research base emphasises that adopting a whole-school approach involving all members of the school community is most beneficial, although it is acknowledged that further evidence is required regarding: 1) primary schools, 2) the English education system, 3) complexity and context and 4) capturing children’s voices. This PhD thesis, therefore, addresses these gaps by asking the question: How do schools use whole-school wellbeing promotion to enable pupils to flourish?Using an exploratory approach through a qualitatively driven mixed methods methodology, the thesis used a three-phase design to address the research problem. Six broad principles formed consistent threads across the findings: 1) enabling children to flourish, 2) integrating wellbeing with key school goals, 3) promoting wellbeing and building capital, 4) building on virtuous cycles, 5) managing complexity and context and 6) evaluating wellbeing promotion through different voices. An additional purpose of the project was to iteratively develop a conceptual model of whole-school wellbeing promotion in primary schools, which is of potential use to professionals and policy makers.