We are excited about how a small pool of neural stem cells (NSCs) generates an incredible diversity of neural cell types. How is this accomplished in an orderly manner to ensure proper brain development? We are finding that developmentally-timed changes in genome architecture play a critical role in determining when and what kinds of cells NSCs can make at any given time. We use Drosophila and mouse to study NSC competence, nuclear dynamics, and temporal fate specification.