Public health in practice: the three domains of public health.

This paper outlines a conceptual model for public health practice by proposing the three domains as a framework to organize and to deliver public health programmes. The model builds on the recognition that public health is everybody's business and therefore, needs a common definitional base. Different levels of skill and a wide range of contributions are needed if public health programmes are to make the most impact. The different domains of practice help to construct a basis for understanding the necessary elements of the public health system and their interactions. Using teenage pregnancy as a case study of a public health programme highlights the characteristics of the model. It demonstrates not only the importance of the role of directors of public health in taking a population-based overview, but also the need for multi-sectoral, multidisciplinary working. The relevance of the public health approach not only to primary care but also to the hospital-based sector becomes apparent, as does its relevance to communities, voluntary sector and local government. Integration of the three domains, a common definition and the framework for the public health system will support effective delivery of health improvement.