Our interest in the coordination of cell cycle control and differentiation has led us to investigate the Caenorhabditis elegans cye-1 gene encoding the G(1) cell cycle regulator cyclin E. We have studied the expression and function of cye-1 by using monoclonal antibodies directed against CYE-1 protein, cye-1::GFP reporter genes, and a cye-1 chromosomal deletion mutation. We show that a ubiquitous embryonic pattern of expression becomes restricted and dynamic during postembryonic development. Promoter analysis reveals a relatively small region of cis-acting sequences that are necessary for the complex pattern of expression of this gene. Our studies demonstrate that two other G(1) cell cycle genes, encoding cyclin D and CDK4/6, have similarly compact promoter requirements. This suggests that a relatively simple mechanism of regulation may underlie the dynamic developmental patterns of expression exhibited by these three G(1) cell cycle genes. Our analysis of a new cye-1 deletion allele confirms and extends previous studies of two point mutations in the gene.