It is known that certain hormones are involved in determining longevity (for example, insulin and insulin-like growth factor). Results presented in a paper published in this week's issue of Science allow us to add steroid hormones to this list. Anne Simon and colleagues show for the first time that a sterol hormone--ecdysone of the fly Drosophila melanogaster--regulates life span. In this Perspective, I discuss the implications of this result in the context of gene regulation and mechanisms of aging.