Belgium is often portrayed as a textbook example of peaceful federalization. Indeed, while the country was for over a century a unitary state, it went through a deep process of federalization in a few decades of time to form a federal state where substate entities enjoy substantial autonomy. Today however, a rather new debate among political elites has emerged: whether to refederalize some of the powers that have been devolved to the substate entities, the Regions and Communities. Such an idea has long been a taboo in federal Belgium, especially among Flemish elites, but the debate seems now more open than ever. In this context, however, little is known about how citizens see this question. Of course, there is a long tradition of surveys including questions on federalism and autonomy devolution. Yet, more qualitative data are needed to understand what motivates citizens’ preferences for more or less autonomy devolution in federal Belgium. The objective of this paper is to explore and compare citizens’ preferences on the Belgian federalization process. In particular, we analyse what motivates the opinion of Belgian citizens in favour of more or less autonomy devolution. To this end, three citizen forums focusing on federalism and democracy over 100 participants were organized in 2017-2018: one in Liège in French, a second one in Antwerp in Dutch and a third one in Elsenborn in German. Their aim was to collect data on all three language communities with an original research design. For several hours, they informed themselves on the topic and discussed federalism and democracy in Belgium. These forums were transcribed and analysed using thematic analysis. Our results suggest that their opinions are justified based on two major argumentative themes: identity and efficiency. While one would expect the former to be of traditional importance, our analysis revealed that considerations about efficiency have taken over the lead among the arguments that citizens use to justify their opinions towards most of the ...