The central premise of the nondelegation doctrine prohibits Congress from delegating its Article I legislative powers. Yet Congress routinely delegates to agencies the power to promulgate legislative rules—rules that carry the force and effect of law just as statutes do. Given this tension between the nondelegation doctrine and the modern regulatory state, some scholars have attacked the nondelegation doctrine as fictional. Little scholarly attention, however, has been given to considering how the central premise of the nondelegation doctrine coheres with—or fails to cohere with—administrative law as a whole. This Article takes up that task, exploring what might happen to administrative law if the Supreme Court jettisoned the central premise of the nondelegation doctrine and frankly admitted that agency rulemaking constitutes an exercise of delegated legislative power. Specifically, this Article analyzes administrative law’s most central doctrines—including the test used to define legislative rules, Chevron and Auer deference, arbitrary and capricious review, procedural due process, and procedural constraints on agency rulemaking—and considers whether these doctrines stand in opposition to or work harmoniously with the nondelegation doctrine. . . .