Joining the European Union has been a long-lasting priority in Turkish foreign policy and one which has fluctuated from relatively short episodes of hope to longer periods of frustration or even despair. The article reviews the intensity, drivers and justification of change during five critical periods: the 1959 application for association that led to the signature in 1963 of the Treaty of Ankara; the request for full membership in 1987 that led to the signature of the Customs Union in 1995; the Helsinki decision in 1999 to grant Turkey candidate status; the unenthusiastic opening of the accession negotiations in 2005; and the gradual evolution toward a transactional cooperation ever since, which coexists with signs of an increasingly adversarial relationship. Foreign policy changes in Turkey are one of the factors explaining the evolution of this relationship. This article emphasizes the need to take into consideration foreign policy changes in the EU and within some of its member states, as well as global and regional transformations. It also points out the extraordinary resilience of EU-Turkey relations, and how pragmatic, ideational and normative arguments have so far contributed to avoidance of an abrupt divorce.