Understanding gene regulatory networks (GRN) that lead to the differentiation of individual neuron classes and the assembly of these neurons into functional cellular networks is critical to the development of the nervous system. In the nematode Caenorhabditis elegans, the 19 GABAergic motor neurons (MNs) are divided into two sub-classes that arise at different developmental stages with different lineages: the embryonic DD and post-embryonic VD MNs. The terminal selector gene unc-30, activates a battery of genes leading to the terminal differentiation of both sub-classes to give the DD and VD MNs the GABAergic fate. A candidate gene approach was used to identify transcriptional regulators of unc-30 and determine whether the DD and VD MNs share the same GRN. The identification of genes regulating unc- 30 in one sub-class but not the other is further evidence of differential GRNs between the DD and VD MNs, and suggests that unc-30 acts as a convergence point between the sub-classes.