The scope, mission and method of contemporary public health.

A coherent public health response is critical to successfully addressing a wide range of issues facing society - from avian influenza through to climate change and obesity. Much can be learned from the long and varied history of public health. From the pioneering work of Ibn Sina to the 'new public health' and recent WHO commission on the social determinants of health, we see that public health has been constantly responsive to emerging concerns. It is also clear that it is not only 'traditional' notions of public health but action from diverse fields has helped to achieve the improvements in health that we now see. However, great inequality in health outcomes remain as we enter the 21st Century. Our challenge as the public health community is to engage diverse groups in advocating not just for health, but also for reductions in poverty and inequality.