The Rules Enabling Act vests in the Supreme Court the power to promulgate rules governing procedure in federal court litigation. The Act, moreover, prohibits the Court from promulgating rules affecting litigants' substantive rights. Courts and commentators have struggled for more than seven decades since the Act's passage to define the boundaries of what rules the Court can and cannot promulgate. In this Article, we undertake to explain the lack of success in defining the contours of rulemaking under the Act and at the same time to glean from our analysis of the Act an important lesson in statutory interpretation. We offer two explanations, operating simultaneously, for why a definitive interpretation of the Act has eluded courts and scholars. First, and perhaps most importantly, the Act's sparse language is arguably susceptible to three alternative and textually plausible constructions. Second, previous constructions of the Act did not pay sufficient attention to statutory interpretation theories in applying one theory or another in interpreting the Act. We conclude that a proper understanding of the theory of statutory interpretation dictates adoption of only one of these constructions - what can be called the incidental effects approach. Under this interpretive model, identified most closely with the Supreme Court's often criticized decision in Burlington Northern, the Court is allowed to promulgate rules that do impact substantive rights, but do so only incidentally - in other words, when the primary goal of the rule is to regulate procedure. We defend this interpretation of the Act by employing a theory of statutory interpretation that directs the interpreter to construe ambiguous text in light of objectively determined background purposes forming a foundation for a particular legislation. Drawing on the pioneering work of Professor Stephen Burbank, we recognize two purposes undergirding the passage of the Enabling Act. Our interpretation promotes both purposes, not elevates one at the expense of the other. In fact, this is where commentators (Professor Burbank among them) have gone astray in their suggested interpretations - they used statutory interpretation theories unmoored from the twin purposes of the Act. In the end, the lesson for statutory interpretation theory largely parallels the lesson to be learned in construing the Rules Enabling Act. In both, when dealing with ambiguous legislation, it is common sense and an attempt to translate underlying purpose, objectively determined, into legal reality, rather than narrow, shortsighted adherence to textual literalism or legislative history, that more effectively further the goals of representative democracy.