Following the collapse of communism in Europe in 1989, the European Commission started supporting domestic administrative reforms in Central and Eastern Europe (CEE) and the Western Balkans in a bid to assist the transition to democratic governance and to promote the development of market economies in the region. Despite having expressed their commitment to European integration since the fall of communism, and having received considerable EU support to introduce reforms in line with EU best practices, standards and principles of administration, some countries fail to show satisfactory progress in line with the EU’s expectations. This thesis explores why that is the case by analysing EU-funded programmes that have been supporting public administration reform in three post-communist countries (i.e. Romania, Serbia and Moldova), over a period of two decades, specifically between 2000-2020. All in all, this dissertation explores the Commission's initiatives and tools that are intended to drive administrative reform in line with European principles of public administration, and assesses their normative and financial input, their implementation, and their impact on the public administration of each country. The study considers the historical legacies of communism in each case study country, as well as the institutional and political dynamics at both the supranational and domestic levels, in a bid to grasp the complexities inherent in the transformation that post-communist states undergo when seeking to become fully-fledged EU Member States. The findings encapsulate the challenges and dynamics involved in the Europeanisation of public administrations in former communist countries and provides insights into the driving forces and barriers that shape the Commission’s ability to ‘Europeanise’ public administrations in EU Member States, Candidate States and Neighbourhood States. Building on desk research, quantitative text analysis and elite interviews undertaken in Romania, Serbia, Moldova, the European Commission and the OECD-SIGMA, this thesis traces the genesis and gradual institutionalisation of the European Commission’s toolkit for supporting domestic administrative reform in line with European principles, and evaluates its implementation over a twenty-year period in each case-study country. Ultimately, the thesis reveals the complex interplay that exists between the Commission’s strategies, the distinct historical and political contexts of each country, and the challenges posed by entrenched legacies of communism in modern societies. The thesis underscores how the effectiveness of the European Commission in fostering meaningful administrative reforms is significantly influenced by wavering political will and commitment for reform within these countries, alongside the Commission's own limitations in imposing effective conditionality and in monitoring the implementation of reforms. It highlights the unique challenges each country faces: Romania, despite being an EU member, struggles with the legacy of centralised governance and the politicisation of the country’s public administration; Serbia’s lack of a credible perspective for joining the EU allows political elites to balance EU conditionalities with internal political dynamics and vested interests; and Moldova, despite having nominally pro-European parties in power, is heavily influenced internally by external geopolitical pressures, particularly from Russia. The study also points to the role of broader geopolitical considerations in shaping the Commission's approach, noting how geopolitical interests, like countering Russian influence or maintaining peace in the Western Balkans, can sometimes overshadow the primary goal of driving administrative reform in keeping with principles of liberal democratic governance. The thesis concludes by emphasizing that while there is a general pro-European discourse in these countries, the actual implementation of reforms that promote efficiency, accountability, and transparency is hindered by deep-seated communist practices and chronic political instability, making it challenging to see the European principles of public administration being adopted in the daily practice of civil servants and systems of public administration from the countries analysed in this thesis. This analysis contributes to a deeper understanding of why the Commission's efforts have seen limited success, despite substantial investment and ongoing efforts to support administrative reform in line with European principles of public administration, thereby offering valuable insights for policymakers, scholars, and practitioners involved in the Europeanisation of public administration.