Constituent power is a key concept of the modern constitutional tradition, yet it encounters serious difficulties when transposed into today’s globalized world. Its radical promise, connected with the "ability to make a new beginning," sits uneasily with a social and political context that seems out of reach and impossible to "constitute." Yet the idea of constituent power continues to animate people in their efforts to reclaim agency and self-government in a landscape shaped largely by others. This article traces key challenges to the continuing force of constituent power in the postnational order and argues that, because of adverse institutional and societal conditions, this order is better understood as post-constituent: ascribing its origin to a pouvoir constituant would, under any plausible conception, stretch the notion too far. If at all, the idea of constituent power survives on a normative plane, potentially feeding a pouvoir irritant of global institutions with a precarious, often technocratic legitimacy basis.