Intro: Traditional health promotion efforts have so far failed to reduce the rise in obesity and chronic disease. Monash Healthâ€™s Health promotion team aimed to change this by adopting an innovative complex systems theory approach to improve the health of the community in South East Melbourne. Methods: Health promotion practitioners at Monash Health use of a range of system mapping tools such as causal loop diagrams, enabling them to gain a deeper understanding of the interconnectedness of the elements influencing a system. This enables the practitioners to see the â€˜bigger pictureâ€™, and identify where initiatives within settings will have the greatest impact. Practitioners use systems theory to work regionally across settings, where people live, learn work and play. Working in settings regionally strengthens the prevention efforts and consistency across the region. Outcomes: Close to 300 settings are supported across the region ranging from education, workplaces, sports clubs, food outlets and other community settings. Using an extended regional workforce information sharing and collaborative relationships between practitioners is now a standard approach and resource sharing is facilitated. An evaluation framework that has the capacity to demonstrate the impact of the systems approach to health promotion has been created. Conclusion: Using complex systems theory to practice health promotion in community health has enabled practitioners to enhance their effectiveness in improving the health of the community. An innovative evaluation framework will evaluate the impact on the community. Key Messages: 1. Strengthening the prevention system 2. Utilising systems tools to identify iniatives and strategies 3. Evaluating the impact of systems initiatives.