In Caenorhabditis elegans, the fates of the multipotent vulval precursor cells (VPCs) are specified by intercellular signals. The VPCs divide in the third larval stage (L3) of the wild type, producing progeny of determined cell types. In lin-28 mutants, vulva development is similar to wild-type vulva development except that it occurs precociously, in the second larval stage (L2). Consequently, when lin-28 hermaphrodites temporarily arrest development at the end of L2 in the dauer larva stage, they have partially developed vulvae consisting of VPC progeny. During post-dauer development, these otherwise determined VPC progeny become reprogrammed back to the multipotent, signal-sensitive state of VPCs. Our results indicate that VPC fate determination by intercellular signals is reversible by dauer larva developmental arrest and post-dauer development.