The underboss, or capo bastone, is second-in-command in the hierarchy of the Mafia crime family. His level of authority varies from family to family, but he is ready to stand in for the boss at any given moment. In the violent and volatile world of the mob, the underboss can easily find himself at the helm of the family so, for the most part, they are usually groomed for an eventual takeover, particularly if the boss’s health is failing or if it looks like he’s headed for a stay in the joint. A family may have two underbosses. An example of this was boss Carlo Gambino, who had Paul "Big Paul" Castellano and Aniello "Mr. Neil" Dellacroce as underboss at the same time. However, one underboss is far more common.