Objective: Schools and the education system are powerful tools for cultivating healthy lifestyles. This research focuses on characterising the factors contributing to the development of health-promoting schools in Israel, and understanding how schools can offer a framework for improving students' health. Fullan's triple change model with its focus on three phases in the change process in schools -- the initiation phase, the implementation phase and the institutionalisation phase -- served as a framework for analysis. Design and setting: This qualitative-constructivist study involved the analysis of data collected from 26 elementary school principals in Israel, 15 of whom belonged to the health promotion school network (HPSN) and 11 who did not. In addition, 10 health promotion leaders from within the schools were interviewed. Methods: Data collection took place by means of semi-structured interviews. in which the questions asked referred to the three phases identified in Fullan's process of change model. We analysed the data using thematic content analysis. Results: Each identified theme was associated with one of the phases proposed in Fullan's model of change. The "initiation" phase included collaboration with key stakeholders, principals' personal commitment, and dissemination of ideas through personal connections. The "implementation" phase included gaining access to appropriate tools and materials, action to deal with barriers to change, and the creation of a holistic health promotion environment. The "institutionalisation" phase included the development of administrative strategies such as adherence to routines, the inclusion of regular events in the school calendar, and the allocation of time frames for the activities undertaken. Conclusion: Fullan's model proved useful in analysing efforts to develop health-promoting schools. The model signalled the importance of using a structured approach throughout the institutionalisation phase in a manner attuned to the unique nature of the school. Alongside identifying key factors that support assimilation, it is crucial to assess their integration into the school culture. The school principal's role is critical throughout all the phases of the development process.