The book focuses on countries having different status vis-a‘ -vis the EU and differently involved, in term of timing, in the EU accession process: some of them are new member states entered in 2004 (Slovenia) or in 2007 (Romania); others were, until recently, acceding countries (Croatia) or candidates to the membership (Serbia). This comparison allows investigation of the power of EU conditionality in different phases of the EU enlargement process.