The accession of ten new member states in May 2004 and the prospective accession of several more in the near future will pose severe budgetary, administrative, and operational challenges for the European Union. But however great, the challenges of enlargement pale in comparison with the challenges of accession that will be faced by the new member states, especially those which until a decade ago were governed by Communist parties that presided over centrally-planned and predominantly-collectivized economies. This paper explores five of the most critical challenges that will face the new member states of post-Communist Europe: 1) administering theacquis; 2) deepening and extending the reform and transformation of the economy; 3) reducing the high levels of unemployment and large government, trade, and current account deficits; 4) financing accession in the face of the EU's budgetary constraints and financial provisions; and 5) coping with all of those challenges in the face of low levels of support for enlargement in many of the member states and high levels of ambivalence and skepticism about membership in most of the new member states. The chapter concludes by noting the low levels of trust in the national government and satisfaction with the way democracy works that exist in most of the new member states and suggests that those low levels of trust and satisfaction will make it difficult for the governments in the new member states to address these challenges while also maintaining sufficient public support to retain office.