Radial glia are specialized cells in the developing nervous system of all vertebrates, and are characterized by long radial processes. These processes facilitate the best known function of radial glia: guiding the radial migration of newborn neurons from the ventricular zone to the mantle regions. Recent data indicate further important roles for these cells as ubiquitous precursors that generate neurons and glia, and as key elements in patterning and region-specific differentiation of the CNS. Thus, from being regarded mainly as support cells, radial glia have emerged as multi-purpose cells involved in most aspects of brain development.