Driven by the EU’s membership conditionality, the ten post-communist Central and Eastern European states engaged in far going reforms of their legal, political and economic systems and underwent changes in their state-society relations. This development culminated in their EU membership in 2004 and, respectively, for Romania and Bulgaria, in 2007. The membership criteria included political and economic expectations, such as the stability of institutions guaranteeing democracy, respect for human rights and the existence of a functioning market economy. In addition, the candidate countries had to harmonize their legislation with the EU’s acquis communautaire before accession and strengthen their administrative capacities. Early on, media, politicians and academic communities voiced doubts about the sustainability of the conditionality-induced impact of the EU on the Central and Eastern European states, arguing that EU transformative leverage will evaporate once the goal of membership is reached. More optimistically, others contended that the EU has successfully “locked-in” political and economic development in the accession states and commands over different efficient tools to exert leverage after accession. Ten years after the completion of the first round of the Eastern enlargement in May 2004, time is now ripe to assess the outcomes and the impact of EU membership on the Central and Eastern European member states. The proposed workshop will evaluate whether the promises of the 2004-2007 enlargement have been fulfilled in core areas of the Copenhagen Criteria: democratic institutions, functioning market economy, compliance with EU legislation and the establishment of administrative capacities. The anniversary provides a good opportunity to assess the complex influence of membership across the Central and Eastern European member states and to advance both our theoretical and empirical understanding of domestic transformative processes triggered by European integration.