Determining the standard of review for administrative actions has commanded judicial and scholarly interest like few other topics. Notwithstanding the extensive debates, far less consideration has been given to the unique features of agencies’ deviations from their own precedents. In this article we examine this puzzle of administrative change. By change, we mean a reversal of the agency’s former views about the best way to implement and interpret its regulatory mandate. We trace the lineage of administrative change at the Supreme Court and analyze features that distinguish agency reversals from other administrative actions. In particular, we contend that because administrative agencies have been given authority to make official pronouncements about the intrinsic meaning of legal texts, agency reversals can carry significant consequences for the rule of law. These consequences are linked to an under-appreciated feature of administrative action: the agency’s chosen mode of reasoning. Agencies sometimes use what we call prescriptive reasoning: weighing evidence, utilizing technical expertise, and making policy choices. At other times agencies undertake what we call expository reasoning: identifying congressional intent and the import of judicial opinions. While prescriptive reasoning yields conclusions about optimal policy, expository reasoning is concerned with what the law is. This distinction activates fundamental rule-of-law interests that should restrain an agency’s discretion to declare that the same document means X today, Y tomorrow, and Z the day after. This Article proposes a new theory and doctrine of administrative change that affords substantial deference in cases where change is based on prescriptive reasoning, but requires de novo scrutiny of reversals grounded in expository reasoning. The proposal strikes an appropriate balance between the need for agency flexibility and the importance of a stable rule of law. administrative law, statutory interpretation, interpretation, stare decisis, precedent, legal change, change, administrative change, rule of law, Chevron, Fox, deference, standards of review, arbitrary and capricious