Résumé : Over the last five decades, European public sectors have undergone a profound process of organizational change, where managerial tools and principles from the private sector have permeated through governments and administrations of many countries. New Public Management (NPM) reform ideas were crucial to this change. Mainstream studies on NPM reforms commonly see it as a mere pragmatic and apolitical framework of reform to downsize State bureaucracies and render public service delivery more efficiently and effectively responsive to users’ demands. Following the Critical Management Studies tradition, this PhD dissertation questions this taken-for-grantedness of NPM and denaturalizes the mainstream idea of NPM reforms as a technical, rational analytic and evidence-based domain. It rather presents them as the result of a historical process marked by politics and power. We choose the European rail industries as empirical context of analysis. Firstly, we examine the EU-driven implementation of NPM reforms in this sector. Secondly, we narrow the focus on the governance of TEN-T, an EU-level investment program in transport infrastructures designed on the basis of key NPM principles. This program is of crucial importance for the full accomplishment of NPM reforms in the national rail industries of the EU. The dissertation is structured in two parts. The first part investigates how NPM ideas developed throughout the political agendas of European national parties and were transformed into actual reform plans by governments. The second part examines how NPM ideas translate into managerial action. Our analysis suggests that the top-down performance-based design of NPM models leads to effectiveness and efficiency improvements in the functioning of public sector organizations which, under certain circumstances, contrast with the most fundamental democratic values of State institutions. These models might thus turn constitutional democracies into technocracies. We conclude by discussing alternatives to NPM, such as the Public Value paradigm.