While commentators celebrate (or lament) the rise of originalism on the Roberts Court, another theory may prove as important to the future of constitutional law: popular constitutionalism. In a range of recent cases, Justices from across the ideological spectrum have proven themselves open to using sources of popular authority to address important constitutional issues. This is especially true of the two Justices at the Roberts Court’s ideological center: John Roberts and Brett Kavanaugh. Even so, the question remains how best to make popular constitutionalism work inside the courts. This question has vexed popular constitutionalists since the theory’s inception. In my view, the answer lies in the search for (what I refer to as) the Constitution’s popular meaning. Put simply, popular meaning is a source of authority rooted in the constitutional status of the American people. While original meaning identifies the best reading of the Constitution’s text at the time of its ratification, popular meaning draws on sources of authority outside of the courts to capture the constitutional views of the American people today. Popular meaning holds out the promise of addressing a range of longstanding theoretical challenges, including how to build a principled form of living constitutionalism and how to make popular constitutionalism work inside the courts. It also offers a distinct lens through which to analyze ongoing debates on the Roberts Court over how best to weigh the authority of post-ratification history — whether framed as arguments from tradition, convention, historical practice, or constitutional liquidation.