This Article is about something federal courts of appeals have done for more than fifty years and more than 600 times. That something is reassignment, a practice where a reviewing court returns a case to a lower court for further proceedings while also directing that those proceedings be conducted by a different trial court judge. Drawing on an examination of the local rules and informal reassignment practices of every federal circuit and district in the United States, as well as an original dataset of 668 decisions in which reassignment was ordered, this Article represents the first scholarly examination of when reassignment happens, who orders it, and how it is ordered. More broadly, this Article uses reassignment as a means to explore the various ways that appellate courts might seek to control trial court judges and influence trial court outcomes. It also discusses what reassignment can teach us about notions of judicial impartiality and neutrality. Finally, this Article discusses reassignment’s implications for familiar debates about whether legal tests are better expressed through rules or standards and the extent to which it is desirable for judges to give reasons for their decisions.