This special issue of Development, Growth & Differentiation is devoted to the development of the nervous system. Although our specific interests in neural development differ depending on our undergraduate education and scientific experience, we are commonly attracted to the magnitude of cellular diversification and striking images of three-dimensional tissue construction events, such as layer formation or wiring. We also anticipate that solving developmental problems will facilitate our understanding of how animal and human brains function. The presence of multiple types of neurons instead of a single set of neurons allows animals to integrate neural information through both the convergence and divergence of signals. Importantly, the initial regionalization step during which each part of the brain primordium develops specificity with closed or exclusive functions must be followed by more integrative brain-forming steps, in which different regions and distinct classes of cells physically intermingle and chemically communicate. In order to advance our understanding of such functional multicellularity in the developing nervous system, this special issue contains pieces from authors with varying interests and expertise in neurodevelopmental events, techniques, and animal models. We hope the ideas presented in this special issue will stimulate discussion and future investigations in the fields of developmental biology and neuroscience.