The functionality of adult tissue stem cells from various organ systems declines during aging. This publication summarizes novel molecular mechanisms responsible for the development of aging-associated deficiencies as discussed by leading experts during the 5th Else Kröner-Fresenius Symposium. It is the first book that explicitly focuses on molecular mechanisms of stem cell aging and its consequences for disease and cancer development including both cell-intrinsic mechanisms as well as aging-induced alterations in the stem cell niche and the systemic environment. Cutting-edge information on stem cells, aging, cancer, and disease make this publication of special interest to basic researchers in the respective fields. Further, it is also intended for medical doctors in the fields of geriatrics, internal medicine, and cancer as it provides a novel understanding of the evolution of tissue dysfunction, diseases and cancer as a consequence of aging.