Much of the pioneering work on the genetics of cell cycle regulation was accomplished using budding and fission yeast. The relative simplicity of these single-celled organisms allowed investigators to readily identify and assign roles to individual genes. While the molecular mechanisms worked out in yeast are more or less identical to those operating in higher organisms, additional layers of control must exist in multicellular organisms to coordinate the timing of developmental events occurring in different cells and tissues. Here we discuss experimental approaches for studying cell cycle processes in the nematode Caenorhabditis elegans.