In recent years, the increasing quantity of waste yearly generated has become a challenge for the European Union (EU) and its Member States (MS). The EU directives on waste have set the regulative path for the MS but the implementation of these provisions have widely diverged at domestic levels, especially between the EU15 and the Members from Central and Eastern Europe (CEE). However, no systemic analysis of the implementation performances among CEE countries has been developed yet. In my doctoral research I wish therefore to fulfil this gap and, by studying the factors of divergence in the performances of CEE countries, to correct shortcomings and contribute to existing debates. In particular, by combining the approaches developed by the literature on Europeanization, on Transnational Integration Regimes and on implementation I wish to verify the effectiveness and the developmental consequences of the European imposition of non-domestic rules in shaping the institutional change in the CEE countries. To do so, I am going to compare three most similar cases, namely Poland, Hungary and the Czech Republic, which have all experienced a similar past in terms of political and economic developments, patterns of pollution, regional agreements, and have been in the group of the five front-runners in the accession process to the EU. However, official reports and data for these countries seem to suggest a cross-country divergence in the implementation and enforcement of waste management practices. Therefore, the research question that I wish to answer is: Why do Poland, Hungary and the Czech Republic differ in their waste management implementation performance? To answer this question, I have developed five preliminary hypotheses and, particularly, I expect that different costs of implementation, the negotiability of sanctions, the attitude of domestic actors in relation to the EU, their integration in transnational learning ties and the discretion of bureaucrats might be relevant in explaining why Poland, Hungary and the Czech Republic had different implementation performances in the waste management sector. I am currently verifying these hypotheses following the methodology of cross-country analysis and process tracing and collecting data through in-depth interviews and archival research. In this paper I will present my key findings.