Because of their ability to generate all the cell types in the nervous system, neural stem cells are promising candidates for the development of cellular and genetic therapies for nervous system disorders and, in particular, neurodegenerative diseases. In recent years, researchers have discovered ways of expanding and perpetuating these cells in culture, as well as different sources for these tissue-specific stem cells, ranging from embryonic to adult tissue, and also from human pluripotent stem cells. Current efforts are oriented to the understanding of the molecular mechanisms controlling their fate decisions, their genetic engineering, and how to harness their potential to make them useful from a therapeutic point of view.