The monetary and payment system consequences of the September 11, 2001, terrorist attacks are reviewed and compared to selected U.S. banking crises. Interbank payment disruptions appear to be the central feature of all the crises reviewed. For some the initial trigger is a credit shock, while for others the initial shock is technological and operational, as in September 11, but for both types the payments system effects are similar. For various reasons, interbank payment disruptions appear likely to recur. Federal Reserve credit extension following September 11 succeeded in massively increasing the supply of banks’ balances to satisfy the disruption-induced increase in demand and thereby ameliorate the effects of the shock. Relatively benign banking conditions helped make Fed credit policy manageable. An interbank payment disruption that coincided with less favorable banking conditions could be more difficult to manage, given current daylight credit policies.