Purpose: The aim of this paper is to identify the role of the principal in establishing a whole school approach for health and wellbeing. Two questions are asked: (1) What do successful Swedish principals do when they take on a whole school approach? (2) How do these results relate to previous research on successful school leadership? Design/methodology/approach: This paper focuses on the complexity of organisational processes and considers the role of successful leadership in managing a whole school approach to health promotion. It presents findings from two different but interlinked projects, and draws on document studies and interviews with principals, student health team members and teachers in Sweden. Findings: This paper argues that successful school leaders are crucial in establishing a whole school approach, because of the work they do to synchronise the health-promoting activities in schools. The study identifies four aspects of coordination that need to be enacted simultaneously when leading health-promoting processes. The fifth aspect identified is that a whole school approach is not limited to the school, but the whole local school context, i.e. a synchronisation between different system levels. Originality/value: Although limited in scale, this paper reports key findings that could have practical implications for school leaders. The study suggests that successful school leadership research needs to use a health-promoting lens in order to make leadership practices health-promoting practices. It also proposes extended comparative research from different fields and contexts.