Depending on how people respond to it, a constitution can cause suffering on a vast scale or lay the foundation for a nation’s liberty, prosperity, and equality. As currently practiced, constitutional theory and interpretation especially concern the meaning, history, and philosophy of constitutional texts. These approaches cannot predict the responses of people to constitutions. Constitutional consequentialism, which I advocate, is a research program that aims to predict the effect of alternative forms and interpretations of constitutions on policy values, especially liberty, prosperity, and equality. This paper discusses two constitutional processes. “Median democracy,” which empowers the median voter, is implemented by referenda and ballot initiatives, special districts (water district, school board, etc.), and winner-take-all elections. “Bargain democracy,” which lubricates bargaining among factions and regions, is implemented by legislatures, comprehensive governments, and proportional representation. I show that median democracy causes stability, whereas bargain democracy ideally causes efficiency and often causes corruption or instability.