Neural specification is regulated by one or many transcription factors that control expression of effector genes that mediate function and determine neuronal type. Here we identify a novel role for one conserved proneural factor, the bHLH protein HLH-3, implicated in the specification of sex-specific ventral cord motor neurons in <i>Caenorhabditis elegans</i> Proneural genes act in early stages of neurogenesis in early progenitors, but here, we demonstrate a later role for <i>
hlh-3</i> First, we document that differentiation of the ventral cord type C motor neuron class (VC) within their neuron class, is dynamic in time and space. Expression of VC class-specific and subclass-specific identity genes is distinct through development and is dependent on the VC position along the A-P axis and their proximity to the vulva. Our characterization of the expression of VC class and VC subclass-specific differentiation markers in the absence of <i>
hlh-3</i> function reveals that VC fate specification, differentiation, and morphology requires <i>
hlh-3</i> function. Finally, we conclude that <i>
hlh-3</i> cell-autonomously specifies VC cell fate.