In this chapter arguments are given to avoid overly-simple views of what causes good and ill health, based on simple associations between proximal risk factors and health status. The author discusses the importance of causal processes to understand why two variables are associated and what this association means; what are the mechanisms of the association, and what other key factors may operate in presumptively causal relationships? It is suggested that an ecological view of health is preferable, with attention to biopsychosocial processes from the micro to the macro levels. Further, it is argued that the role that the physical and social environment plays in determining the public’s health is of particular importance to health promoters. This calls for research models that embrace intra-personal, psychosocial and social/cultural processes. Building on the Ottawa principles for health promotion the chapter introduces a model for a whole community approach to health improvement. The model shows how the multi-level processes in community settings and at different system levels shape health. Further, the model makes it clear that understanding these processes are beyond the interests and expertise of any one health discipline and therefore inter-disciplinary approaches are needed.