The development and function of the nervous system is orchestrated by a plethora of gene regulatory mechanisms. MicroRNAs (miRNAs), an abundant class of small non-coding RNAs, are emerging as important post-transcriptional regulators of gene expression in the brain. MiRNAs function at all stages of neuronal development, ranging from the initial specification of neuronal cell types to the formation and plasticity of synaptic connections between individual neurons. Moreover, links between miRNA dysfunction and neurological diseases become more and more apparent. The study of this novel layer of gene regulation therefore promises to enrich our knowledge of brain function and pathology.