Schools have a key role to play in promoting healthy wellbeing and in teaching the skills important in protecting against mental illness. However, navigating the array of wellbeing practices, initiatives, and programs with a view to deciding which of these are appropriate in any school setting is a challenge. Although current best practice is to adopt a whole-school approach to wellbeing, what this means in context can also be unclear within the complex, multi-faceted school environment. Taking inspiration from a systems-informed perspective of school wellbeing, this article describes an organisational tool to assist school staff in understanding and capturing the elements of a whole-school approach in their own context. Using the analogy of a tree, the key components of a whole-school approach to wellbeing are outlined with examples drawn from current research literature and existing wellbeing conceptual frameworks. Through the use of this wellbeing tree tool it may be possible to appreciate the "bigger picture" of a whole-school approach to wellbeing that links current practices to the overall vision and mission of the school. The article concludes with a reflection on the extent to which this tool is fit for purpose, its limitations, and how it could be extended.