Federalism is a debated issue in the French political culture, which constantly evokes the French Revolution and the struggle between the Girondists and the Jacobins. This chapter revolves around the mechanisms of the emergence of the federalist idea in political debates during the eighteenth-century from the Old Regime to the Revolution. It pays attention to the contexts which built a family of words around a territorial reorganisation of the state connected to both reform and revolution, and highlights how this perspective implies considerations on wider issues as the separation of powers, the idea of republic, the relationship between the legislative and the executive powers, sovereignty and democracy. Through an accurate semantic analysis, it aims at distinguishing the stage of the political project from the moment of the manipulation of the tenet of federalism.