This introductory chapter distinguishes between two periods, namely the accession phase, when at that time candidate Central and Eastern European (CEE) countries engaged on the accession journey to the EU and, respectively the ultimate phase of integration of the European acquis after joining the EU. It is argued that while the 1st phase is over, the 2nd is still going on. Whereas the most remarkable advances in harmonizing domestic legal and institutional frameworks with the European ones took place during the accession timeframe, once countries joined the EU, setbacks in the realization of international labour rights have been noted in areas insufficiently regulated. In terms of substantive matters, it points out that the impact of the EU acquis has been very strong in areas such as equality, health and safety, labour migration, business restructuring and working conditions, including regulation of new forms of employment—fixed term contract, temporary agency work, part time, working time and “soft” collective labour rights—information and consultation, and works councils. One of the areas where there is still a need for clear and consistent policy and legislative intervention at the level of the EU is collective bargaining. Furthermore, it elaborates on the latter and concludes on the legal gaps, which should be filled in the near future, including an European definition of the term “worker” and a regulatory framework for collective bargaining.