The Notch signaling pathway has long been known to influence cell fate in the developing nervous system. However, this pathway has generally been thought to inhibit the specification of certain cell types in favor of others, or to simply maintain a progenitor pool. Recently, this view has been challenged by numerous studies suggesting that Notch may play an instructive role in promoting glial development. This work has inspired a new look at the role of Notch signaling in specifying cell fate. It has also prompted further consideration of the emerging view that in some contexts glia may be multipotent progenitors. This review examines the role of Notch during gliogenesis in both fruit flies and vertebrates, as well as evidence in vertebrates that some glia may be stem cells.