http://news.sciencemag.org/biology/2015/10/reprogrammed-stem-cells-work-well-those-embryosResearchers who hope to use stem cells—the unspecialized cells that produce all of our tissues—to treat diseases face a dilemma. Stem cells from embryos (ES cells) could provide a wealth of new cells but spark ethical objections. Stem cells produced from adult cells (so-called induced pluripotent stem [iPS] cells) avoid the ethical difficulties, but some scientists have questioned whether they are as powerful as ES cells. A new study suggests that the two types of stem cells are equivalent and may help soothe worries about the capabilities of iPS cells.