["JCMS: Journal of Common Market Studies, EarlyView. ", "\nAbstract\nIn recent years, the process of EU enlargement has become increasingly difficult. The longer the process drags on and the less likely accession appears, the more the candidate states are discouraged and the less influential the EU becomes. A different approach to integration must therefore be used. The notion of differentiated integration is increasingly mentioned in this regard. Still, notwithstanding the immense opportunity that decentralised agencies represent for implementing differentiated integration, their potential for maintaining EU influence over the candidate countries has hitherto hardly been systematically assessed. In this article, I present the first comprehensive analysis of the co‐operation between candidate countries and decentralised agencies over the last 20 years. Drawing on a novel dataset, I show that candidate countries' co‐operation with EU agencies is shaped by more than the traditional foreign policy and functionalist logics. It varies across formal and ad hoc forms, reflecting the foreign‐policy sector‐specific priorities of EU institutions and tasks interdependence of EU agencies. Moreover, I show that agency independence can act as a moderator in the responsiveness of EU agencies to EU central institutions preferences. Finally, this article shows that administrative capacity is an important factor in enabling the external differentiated integration of candidate countries in EU agencies. These findings have important implications for the study of external differentiated integration, and they reveal a more fragmented picture of EU external governance than previously recognised."]