Over the last decades, the management of public finance in Belgium has faced a dramatic transformation due to two programmes of government related to major institutional reforms: Belgian fiscal federalism and European fiscal governance. How have both programmes of government reshaped Belgian regions? And, in turn, how have the reactions of the latter reshaped both programmes? In order to answer this question, this thesis concurs to the development of an “analytics of public finance government”, through a dialogue between the emerging political sociology of public finance and Michel Foucault’s work – as well as his successors’. The implementation of this innovative theoretical framework to the study of five selected controversies sheds light on the “neoliberal” feature of the apparatus of regional public finance government currently at work in Belgium. This apparatus presents two complementary features – which correspond to the two “faces of the State” in the neoliberal era: consolidation and competition. While the pubic investment policy is under stress, it is argued that the main answer provided so far (the increasing use of public-private partnerships – PPPs) tends to spur the marketization and (quasi-) privatization of public service in Belgium.