As animals transition into adulthood, males and females undergo sex-specific developmental changes that affect both morphology and behavior to maximize fitness. Juveniles primarily adopt new behaviors upon maturation through modification of existing neural circuits, which must occur at the appropriate time during development. In the C. elegans nervous system, most neural circuits are fully formed by the L3 larval stage; however, there are a few examples of neurons with delayed maturation. One is that the embryonically derived HSNs generate synapses onto the vulval muscle at the L3 and L4 larval stages. In addition, several existing neural circuits appear to undergo significant modulation through gene expression changes, particularly in males, during the juvenile-to-adult transition. For example, juvenile males and hermaphrodites have similar levels of the chemoreceptor odr-10 in the sensory neuron AWA; however, upon maturation males specifically downregulate expression of this chemoreceptor. Similarly, males upregulate expression of srj-54 in the interneuron AIM during this transition. These gene expression changes likely mediate the activation of adult behaviors; however, it remains unclear how their onset is regulated. In nematodes, it is known that the heterochronic pathway controls developmental timing by regulating stage specific events. Although this pathway has been carefully characterized in seam cells, its functions in the nervous system are not well understood. We are using odr-10, srj-54, and other genes as molecular markers for nervous system maturity, allowing us to investigate whether the heterochronic pathway regulates nervous system maturation. Surprisingly, our results suggest that several important heterochronic genes, such as daf-12 and lin-41, may not be important for this process. However, we find that lep-5, a newly identified heterochronic gene, is essential for juvenile-to-adult changes in the expression of odr-10 and srj-54. Thus, a previously uncharacterized branch of the heterochronic pathway may be important for developmental timing in the nervous system.