In Caenorhabditis elegans, the forkhead protein DAF-16 transduces insulin-like signals that regulate larval development and adult lifespan. To identify DAF-16-dependent transcriptional alterations that occur in a long-lived C. elegans strain, we used cDNA microarrays and genomic analysis to identify putative direct and indirect DAF-16 transcriptional target genes. Our analysis suggests that DAF-16 action regulates a wide range of physiological responses by altering the expression of genes involved in metabolism, energy generation and cellular stress responses. Furthermore, we observed a large overlap between DAF-16-dependent transcription and genes normally expressed in the long-lived dauer larval stage. Finally, we examined the in vivo role of 35 of these target genes by RNA-mediated interference and identified one gene encoding a putative protease that is necessary for the daf-2 Age phenotype.