This broad ranging study explores the recent findings in the dynamic field of molecular biogerontology. It examines the numerous molecular changes which occur during senescence and pinpoints the basic biological pacemakers of aging. Investigators examine the importance of DNA damage and the extent of differential gene expression during aging. There are discussions of attempts to manipulate the lifespans of various model organisms through gene transfer and regulated gene expression. Throughout, the contributors stress that the genome holds the ultimate key to understanding the limits of lifespan and the determinants of senescence.