Since their realization that United Airlines Flight 93 was headed toward the U.S. Capitol on the morning of September 11, 2001, legislators and policymakers have been debating how the legislative branch would continue functioning in the aftermath of a terrorist attack that killed or incapacitated large numbers of sehators or representatives. This Article reviews the current House and Senate "Continuity of Congress"plans, and argues they are both practically and constitutionally inadequate. Focusing particularly on the Constitution's majority quorum requirement in Article I, Section Five, Clause One, this Article argues that a House or Senate operating in accordance with the current rules of those two bodies after a catastrophic attack would lack the basic constitutional structure to do business. The problem would be especially intractable in the House of Representatives, because seats in that chamber can only be replenished through elections. Because the rule-making power granted to the legislative branch in Article I, Section Five, Clause Two is insufficient to fix this twenty-first century problem, this Article endorses a constitutional amendment that would establish an orderly postdisaster replenishment process.