MicroRNAs (miRNAs) are integral parts of the gene regulatory networks that control most developmental processes. Through their regulatory action, miRNAs introduce an additional layer of genetic complexity that can translate into increased cellular diversity, something that is extremely relevant to nervous system structure. In addition, miRNAs sharpen the spatial and temporal boundaries between different cellular states during development. Here, we illustrate these roles with a number of specific miRNAs that act during distinct steps of neural development. We further discuss specific aspects of miRNA function that make these regulators particularly suited to provide the robustness and complexity that are essential for the dynamic nature of both the development and activity of the nervous system.