The Europeanisation of candidate countries and new members is a rather recent and still comparatively small, but - particularly since 2003 – a fast-growing research area. Research in this area has developed primarily in the context of the EU’s eastern enlargement. More recently, a small number of theoretically informed, book-length studies of the EU’s influence on the East Central European candidate countries have established the Europeanisation of applicant states as a distinctive research area. These studies fit within a common conceptual framework, which draws on the debate between rationalist and constructivist institutionalist theories in International Relations and Comparative Politics. This framework makes these studies highly compatible with analyses of the Europeanisation of member states, with which they share one key empirical finding, namely that the impact of the EU on candidate countries is differential across countries and issue areas. On the other hand, the theoretical implications of these findings appear more clear-cut than in the case of the Europeanisation of member states: rationalist institutionalism, with its focus on the external incentives underpinning EU conditionality, and on the material costs incurred by domestic veto players, appears well suited to explaining variation in the patterns of Europeanisation in candidate countries. The next stage of this research agenda concerns the impact of accession on the dynamics of pre-accession Europeanisation and how durable the patterns of candidate Europeanisation are in the post-accession stage.