Cellular senescence is a distinctive form of cell cycle arrest that has been suggested to modulate the processes of tumor suppression and aging. Though a detailed understanding of the cellular machinery regulating this process is emerging, a more thorough understanding of the key players linking senescence to organismal aging is needed. The recent discovery that loss of the p53-related protein p63 induces cellular senescence and causes features of accelerated aging provides further evidence that cellular senescence is intimately linked with organismal aging, and identifies p63 as a key regulator of both of these processes.