The EU is seeking to repeat the success of its eastern enlargement in the Western Balkans.The accession of Croatia on 1 July 2013 provides a template for other Western Balkan states to emulate as they seek to transpose and implement the EU acquis communautaire and advance their membership prospects. But the EU’s engagement with the Western Balkans is proving uneven and unsatisfactory: the enlargement process is now on ‘life support’ and ‘flat lining’ along a trajectory of ‘frozen negotiating chapters’ and mutual mistrust toward (despite the promise made at Thessaloniki a decade ago) an increasingly uncertain destination.The main reason for this is ‘enlargement fatigue’ amongst the Member States of the European Union.This article explores the underlying causes of this phenomenon and how it is impacting on the EU’s relationship with the Western Balkans. It demonstrates that there is a symbiotic link between enlargement fatigue on the EU side of the relationship and the deficit of implementation on the candidate state side.The extended economic crisis which has so damaged EU solidarity has also had a knock-on impact on enlargement: the previously successful ‘external incentives model’ has run aground on the rocks of growing mistrust and pervasive uncertainty about the endpoint of the process.