There are a number of influences on how long an agency head serves. The importance of particular influences, in turn, depends on the prospective destination of the agency head: elsewhere in the public sector, the private sector, or retirement. The authors estimate survival models of agency heads’ tenure using panel data on British central government executive agencies from 1989 to 2012. Findings suggest that chief executives of poorly performing agencies are encouraged to retire sooner. There is no evidence that a change in political control increases the risk of any form of exit, suggesting that political pressure to leave is not substantial for this type of official. Outsiders—agency heads recruited from outside central government—are relatively difficult to retain for a longer time, such that potential shortfalls in suitable managers caused by retirements in an aging workforce may be difficult to make up by appointing from this source.