Written and edited by experts in the field, this collection examines recent progress in our understanding of stem cell biology and how the properties of stem cells can be manipulated for therapeutic purposes, emphasizing the roles that cutting-edge technologies and interdisciplinary approaches have played in this work. The contributors describe how the first cell lineages arise in the mammalian embryo, stem cell dynamics during the development and homeostasis of specific tissues, and what happens when stem cell integrity is compromised. They also explore specialized niches in which stem cells reside and how the extracellular cues in those microenvironments regulate stem cell behavior.