The author distinguishes between normative and positive constitutional economics. Taking the observation that the normative branch of the new discipline is much better developed than its positive counterpart as a starting point, the available positive literature is surveyed nevertheless. The available evidence is arranged into four categories: (1) Constitutional rules and the procedures bringing them about, (2) constitutional rules as the result of preferences and restrictions, (3) constitutional rules channeling constitutional change, and (4) the economic effects of constitutional rules. Additionally, various concepts of the constitution are presented, the tools suited for a positive theory of constitutional economics discussed, and precursors as well as related research programs shortly described.