Foreword from Dr Margaret Chan, Director-General, WHO: Population ageing is a global phenomenon that is both inevitable and predictable. It will change society at many levels and in complex ways, creating both challenges and opportunities. On the one hand, older people already make a significant contribution to society, whether it is through the formal workforce, through informal work and volunteering or within the family. We can foster this contribution by helping them maintain good health and by breaking down the many barriers that prevent their ongoing participation in society. On the other hand, towards the end of life, many older people will face health problems and challenges to their ability to remain independent. We need to address these too, and do it in a way that is affordable and sustainable for families and society. Good health must lie at the core of any successful response to ageing. If we can ensure that people are living healthier as well as longer lives, the opportunities will be greater and the costs to society less. This great demographic challenge of the first half of the 21st century therefore demands a public health response, and WHO has identified this as a priority for the Organization. Numerous determinants of healthy and active ageing lie beyond the health system. They also start to exert their influence atearlier stages in life. Our response, therefore, needs to tackle issues across the life course and in many social spheres. But the health sector, too, needs to adapt. Overwhelmingly the health challenges in older age are the consequence of noncommunicable disease. We need to develop health systems which can provide the chronic care that these diseases and their risk factors require. This global brief takes a fresh look at existing health data and draws on some exciting new work to help us better understand exactly what these needs are. It identifies action we can all take. It is now up to the global community to take up the challenges it identifies and truly add life to our increasing years. Read the full WHO global brief here.