We study the simple larval nervous system of our closest invertebrate relatives, the tunicates. Tunicates, like us, belong to the Chordate phylum, but have very simple embryos and compact genomes. The laboratory model tunicate Ciona has only 177 neurons and is the only chordate with a fully mapped "connectome". We take advantage of this simplicity to understand molecular mechanisms that may underlie human neurodevelopment. We use transcriptome profiling to assay global transcriptional dynamics in neural progenitors during Ciona development, and use CRISPR/Cas9 to knock out important transcription factors and their downstream targets to understand how these gene networks control neuronal specification, morphology, physiology, neurotransmitter identity, and connectivity.