The neuron is a highly polarized cell that processes and transmits signals among different components of neural circuitry. This coordinated signaling process relies, in part, on the complexity and relative abundance of the proteins in the different structural and functional domains of the neuron: dendrites, axons and presynaptic nerve terminals. Previously, it was hypothesized that the local proteome of each domain is maintained by the transport of proteins synthesized in the parental soma. However, accumulating evidence indicates that a variety of RNA molecules (protein-coding and non-coding) are transported and localized to specific neuronal compartments, where they regulate many fundamental neuronal functions. Furthermore, the compartment-specific targeting of mRNAs and their local translation plays important regulatory roles in neuronal processes including synapse formation and dendritogenesis, as well as axonal guidance and plasticity. Here, we review current knowledge of mRNA localization, the functional significance of local protein synthesis in neuronal subcellular domains and examine the regulation of mRNA transport and expression in various animal model systems.