During the liberal age, the role of parliaments as mechanisms of diffusion of economic thought became particularly relevant concerning the ongoing process of spread and institutionalisation of political economy. Scholars have acknowledged that 'the sometimes active role played by economists in the political sphere was an essential part of a broader process of dissemination of economic ideas and of institutional consolidation of economic science that took part in the 19th century and continued in later periods, although at various speeds and encountering obstacles of varying degree in different local circumstances'.3 This view explains the recent increase in the production of scientific works concerning not only the institutionalisation of economics in different countries, but also the circulation of ideas, the evolution of the economic thought in diverse nations, and the relationship between ideas and economic policy. This dissertation follows this approach. Specifically, the aim of this research is to analyse the presence and diffusion of economic ideas in the parliamentary environment in Spain during the last third of the 19th century, and to explore how the parliament contributed to the process of institutionalisation of political economy in this country during this period, when this process was definitively consolidated. This objective has been achieved through the analysis of two sets of parliamentary economic debates, which took place at two crucial periods of the last third of the 19th century (the first in the aftermath of the liberal revolution of 1868 and the second at the end of the first part of the Bourbon Restoration), and through the study of the connections of the parliament with other institutions (namely universities, economic societies and economic periodicals) taking part contemporarily in the process of diffusion and institutionalisation of political economy. Finally, in order to explore the peculiarity of the Spanish case and place it in an international context, a comparison between the processes of institutionalisation of political economy in Spain and Italy has been undertaken.