The force of a constitution, like the force of all enacted law, derives, in significant part, from the circumstances of its enactment. Legal and political theory has long recognized the logical necessity of a “constituent power.” That recognition, however, tells us little about what is necessary for the successful enactment of an enduring constitution. Long-term acceptance of a constitution requires a continuing regard for the process that brought it into being. There must be, that is, recognition of the “constituent authority” of the constitution-makers. This paper is a consideration of the idea of “constituent authority” drawing on a comparison of various constitutional systems.