This investigation will seek explanations of the recent poor performance of mortality among older women in the United States, relative both to older men and to women in previous eras. It will investigate causes of death responsible for the slowdown in their rate of mortality advance, and will study the role of changes in risk factor distributions. Particular attention will be paid to the role of cigarette smoking histories and to obesity. An effort will be made to combine information on changes in risk factor distributions with estimates of their mortality consequences. Data will be drawn from published and unpublished sources produced by the National Center for Health Statistics as well as from epidemiologic studies.