After the collapse of communism in Central and Eastern Europe (CEE) we have been witnessing an increased scholarly interest in democracy development in this part of the world. Within such developments the European Union (EU) seems to have played an important role in the modes and characteristics of democracies and fundamental rights established in the region. This is true for candidate countries where a conditionality strategy has been the strongest one, but also for potential candidates and the partners in the new neighbourhood policy. The purpose of our research has been to analyse the impact of the EU on the quality of democracy in selected post-communist European countries. More precisely, our interest is to compare the EU’s influence on the quality of democracy in new EU member states, such as Poland, Hungary, Bulgaria and Romania; in potential candidate countries, such as Serbia and Albania; in neighbour countries, such as Ukraine; and in more remote countries affected by EU policies, such as Armenia. We decided to choose countries with different status vis-à-vis the EU, as this seems the best way of comparatively assessing the different impact of the EU in influencing those democracies. Thus, this research is going to explore in more depth a topic that has been discussed during these years along a number of different perspectives and dimensions (see Diamond and Morlino 2005). To better focus our research we decided to concentrate on understanding how the constitutional designs of the CEE countries we mentioned above have been effectively implemented, achieving or not achieving some characteristics of democratic quality, and to what extent this was the result of the action of the EU. Accordingly, the next section will suggest a definition of quality of democracy (QD), focus on the main empirical dimensions that are relevant for assessing the constitutional design and its implementation, and point out the main connections with the other procedural dimensions. The subsequent four sections will deal with the main aspects where the key salient dimension, that is, inter-institutional accountability, can be seen tested. They include: relationships between executive and legislative power; constitutional justice; decentralization and regionalism; and other institutions of accountability such as the Ombudsman. In each section a few issues for research on the specific cases will be suggested. In the conclusion to this introduction the main empirical hypotheses the research should control are presented.