Abstract: Nearly all of us who participate in constitutional argument in subjective good faith share a second-order methodology of constitutional decision-making—that is, an approach to working out both our first-order theories of constitutional interpretation and our judgments about appropriate results in particular cases. That shared method involves a search for reflective equilibrium between our prior or intuitive methodological assumptions (which sometimes may be vague or indeterminate) and our intuitive judgments concerning the appropriate results in particular cases. If our ex ante methodological theories are underdeterminate, reflection on new cases’ facts will lead us to specify our premises more fully. Moreover, in instances of initial conflict between judgments of desirable case-specific outcomes and previously adopted methodological commitments, the Reflective Equilibrium Hypothesis advanced in this Essay holds that adjustment can occur on either end. If we argue about constitutional issues in good faith, normally we will adapt our judgments concerning correct results to methodological premises that we have previously endorsed. But sometimes reflection on new cases will provoke an elaboration, qualification, or rethinking of methodological commitments. After advancing the Reflective Equilibrium Hypothesis as an explanatory theory of the main currents of constitutional argumentation, this Essay offers a brief normative defense.