For over a decade, the National Bureau of Economic Research has sponsored the Economics of Aging Program, under the direction of David A. Wise. The program addresses issues that affect the well-being of individuals as they age and a society that is composed increasingly of older people. Within the next 20 years, an unprecedented proportion of Americans will be over 65. New research in the economics of ageing is an essential element of understanding what the future holds for this ageing population. This text presents both empirical papers that consider questions that are fundamental to public policy and more theoretical contributions that lay groundwork for future research in the economics of ageing. The text provides an overview of some of the most important questions facing researchers on aging and outlines new techniques and models that may help to answer these questions.