Below the surface of everyday school environments lays an invisible system of resources and opportunities just waiting to be utilized for mental health promotion. This ethnographic study looked inside two schools to create a better understanding of real world practice and consider what could be better articulated and quantified. Findings suggest that mental wellbeing was promoted by a complex interaction of people, settings, policies, programs and practices, all constrained by the schools’ most precious resource, time. Potentially valuable aspects of the school environment were observed, including interaction networks, proactive staff behaviours, and contrary practices (actions lacking coherence to professed school values and wellbeing goals). All the ways in which schools promote mental health could not be quantified. But more things can be counted and doing so may raise the schools’ sensitivity and capacity to promote wellbeing. Options for articulating and better harnessing the invisible mental health promotion system are outlined.