Abstract: Private law—the background legal rules of contract, property, and tort—determines legal entitlements to the material goods dealt with by constitutionally guaranteed economic and social rights. Courts have struggled to determine whether and how the constitution applies to private law. The jurisdiction of constitutional courts sometimes leads them to “develop” private law in light of the constitution. Once we recognize that many of the questions that have puzzled courts and commentators about the application of the constitution to private law actually involve puzzles about the constitution’s substance, most of the analytic difficulties are transformed. The questions that remain arise from specific institutional arrangements, and in particular from the distribution of law-declaring authority between constitutional and ordinary courts.