Historians and political theorists have long been interested in how the principle of people’s power was conceptualised during the French Revolution. Traditionally, two diverging accounts emerge, one of national and the other of popular sovereignty, the former associated with moderate monarchist deputies, including the Abbé Sieyes, and the latter with the Jacobins. This paper argues against this binary interpretation of the political thought of the French Revolution, in favour of a third account of people’s power, Sieyes’ idea of pouvoir constituant. Traditionally, constituent power has been viewed as a variation of sovereignty, but I show it to be an independent conceptualisation of people’s power. Sieyes’ political theory led him to criticise and refuse contemporary theories of sovereignty in favour of what he understood as a fully modern account of people’s power. Based on extensive research in the archives, I show how Sieyes opposed the deployment of sovereignty by the revolutionary Assemblies and recommended replacing it with the idea of constituent power.