This chapter adopts the working assumption that it is conceivable that at some time in the future it would be in the interest of the United States to restructure its sovereign debt (i.e., to reduce the principal amount). It addresses in particular U.S. Treasury Securities. The chapter first provides an overview of the intermediated, tiered holding system for book-entry Treasuries. For the first time the chapter then explores whether and how — logistically and legally — such a restructuring could be effected. It posits the sort of dire scenario that might make such a restructuring advantageous. It then outlines a novel scheme of exemptions and certifications that would enable the U.S. to selectively default as to only some of its debt owed to certain holders — this, even though the U.S. cannot actually know who holds the vast majority of its Treasury Securities. Next, the chapter outlines three alternative approaches to a restructuring. Under two of the approaches a fraction of the debt would be replaced by “Prosperity Shares” — non-debt securities that would provide creditors with a share of future upside economic growth.[...]