Abstract: This Essay uses the Court's shifting doctrines of judicial deference to agency interpretations of law to examine larger questions about the Legal Process approach to interpretation. Since the New Deal, the Court has adopted several distinctive deference regimes. First, the Hearst-Packard framework predicated the availability of judicial deference on a nonexclusive, multifactor test that asked, in effect, when it made sense, under all of the circumstances, to assume that Congress would want a court to defer. Second, the Chevron doctrine adopted a more categorical approach that instructed courts generally to defer to an agency's "reasonable" interpretation of a statute the agency administered. Third, the Mead doctrine, which is the Court's current approach, takes the intermediate position. Mead gives Chevron deference to agency interpretations announced through notice-and-comment rulemaking or formal adjudication. However, Mead also leaves open the possibility that other, unspecified factors might disclose a legislative intention to delegate interpretive lawmaking power to an agency outside those safe harbors. This Essay argues that all of these seemingly diverse approaches reflect a common foundation. They all grow out of the methodology of Legal Process School, which directs judges (a) to presume that legislature consists of "reasonable persons pursuing reasonable purposes reasonably" and (b) to read statutes accordingly. In determining appropriate deference frameworks, the Justices have almost never looked into the original meaning (if any) of the judicial review provisions of the Administrative Procedure Act (APA). Nor have they explored the background legal expectations (if any) against which those provisions were enacted. Rather, virtually every Justice to address the question has asked, in effect, what deference framework a hypothetical reasonable legislator might prefer. Whatever else, this phenomenon tells us that Legal Process reasoning continues to exert a hold on the broader legal imagination—even, on occasion, that of the Court's textualists.