AbstractOne of the goals in developmental biology is the identification of key regulatory genes that govern the transition of embryonic cells from a pluripotent potential to a specific, committed cell fate. During vertebrate skeletal myogenesis, this transition is regulated by the MyoD family of genes. C. elegans has muscle analogous to vertebrate skeletal muscle and has a gene(hlh‐1) related to the MyoD family. The molecular and genetic characterization of hlh‐1 shows that it is very similar to the vertebrate MyoD family in many respects, including its expression pattern and DNA binding activity. The hlh‐1 product is required for proper myogenesis, but it is not required for myogenic commitment during embryogenesis in the nematode. The role of this MyoD‐related gene in nematode myogenesis is discussed and compared to those of the vertebrate MyoD family.