In this Article, Professors Farber and O’Connell argue that the reality of the modern administrative state diverges considerably from the series of assumptions underlying the Administrative Procedure Act (APA) and classic judicial decisions that followed the APA. These assumptions called for statutory directives to be implemented by one agency led by Senate-confirmed presidential appointees with decision-making authority. The implementation (in the form of a discrete action) is presumed to be through statutorily mandated procedures and criteria, with judicial review to determine whether the reasons given by the agency at the time of its action match the delegated directions. They describe in depth this lost world on which current administrative law is based. They go on to explain how the realities of the modern administrative state have come to differ greatly from the intended circumstances. They then weigh the benefits and costs of this shift, tentatively concluding that the costs trump the benefits. Finally, they conclude that returning to this lost world is impossible and instead propose some possible reforms in all three branches of the federal government to make the match between current realities and administrative law stronger.