Since its creation back in 1998, the European Central Bank (ECB) has gradually evolved both in its role as a core manager of the single currency and by acquiring new roles and tasks. The latter entails most obviously the ECB’s supervisory tasks within the Single Supervisory Mechanism (SSM), as well as its various unconventional measures aimed at saving the euro and pushing for economic policy reforms in the context of the financial and sovereign debt crisis. One dimension of the ECB’s activities that has also increased over time concerns its international cooperation. . The ECB established progressively close cooperation with central banks and financial institutions worldwide, joined relevant international organizations, and participates in various informal international fora and networks. This paper examines the evolution of the ECB’s international dimension with a view to assess its transformative effects and side effects on the ECB of today.