This chapter looks at political and legal accountability in the European Banking Union. It is structured as follows. The discussion begins with a sketch of the constitutional structure and administrative machinery in the area of Banking Union. The focus then shifts to the concept of accountability, in an attempt to explain key concepts that will be used in this paper. This is followed by analysis of political accountability in the Single Supervisory Mechanism and the Single Resolution Mechanism, which are the main building blocks of the Banking Union thus far. The paper examines the respective roles of the European Parliament, Council, Eurogroup and national parliaments in holding the Banking Union actors accountable for the exercise of their duties. The penultimate section of the chapter concerns internal administrative review of supervisory measures and resolution actions, which is carried out by the Administrative Board of Review and the Appeal Panel respectively, as well as review by the Court of Justice of the European Union and national courts. The final section of the chapter glimpses briefly the vexed issue of the European Central Bank’s legitimacy in exercising supervisory tasks over banks in the Euro area (and potentially beyond).