The paper distinguishes two contrasting models of accountability, one based on principal-agent relations, which is backward-looking, the other a dynamic and forward-looking model. The paper argues that this second model of accountability is more appropriate for independent bodies like the ECB/SSM and the SRB, operating in technically complex, rapidly evolving environments under conditions of high uncertainty, where parliaments and other political authorities have very limited sanctioning powers. It then goes on to review the nature and effectiveness of three main forms of accountability as applied to these institutions – administrative, judicial, and political – together with the contribution of external review bodies, such as the European ...