The aim of the chapter is to show the profound semantic transformations undergone by four key political concepts - citizenship, constitution, federalism, and liberalism - in the Spanish Atlantic at a time of imperial revolutions such as the first decades of the nineteenth century. Naturally, the great controversies surrounding these concepts and their associates that took place in those immense territories can only be summarized at the cost of a stylization of the most important changes. To this end, this essay draws on the results of the collective research project known as Iberconceptos, in which we set out to compare the trajectories of some twenty basic concepts in the Iberian territories on both sides of the Atlantic. The work emphasizes the inevitably experimental nature of the decisive political changes that took place in those years, and highlights the point of view of the actors, who faced with the conceptual tools available the imperative need to find answers to the extremely serious constitutional challenge triggered by the sudden displacement of the monarch considered legitimate (Fernando VII) from the throne of Madrid. This exceptional situation led them to propose new legal-political concepts and to try out new institutional arrangements.