Written by an international group of experts, this year's review first considers the methodological and design dilemmas faced in conducting centenarian research. It then offers guidance in locating literature and data sources for primary and secondary information on centenarians and the oldest old. This section includes a list of the world's oldest persons and discusses the difficulties in compiling such a list. The remainder of the review is divided in three sections-the biology and genetics of longevity, the behavioral and social predictors of longevity, and methodological issues in qualitative and anthropologic approaches and the study of the very oldest old, supercentenarians, or those who live to 110 years or more. Data is drawn from studies undertaken among populations in diverse parts of the world.