While the EU agencies that have been granted the power to adopt binding decisions are a diverse group, they at least share one feature: in all of them an organisationally separate administrative review body, i.e. a board of appeal, has been established. The review procedures before these boards must be exhausted before private parties can seize the EU courts and the boards therefore all fulfil a similar function: filtering cases before they end up before the courts and providing parties by expert-driven review. Sharing this common function as well as some common features, the boards of appeal of the different agencies remain heterogenous in their set up and functioning. This raises a host of questions from both a theoretic and practical perspective which this volume analyses in depth: how do the boards function, which kind of review do they offer, and how should they be conceptualized in the EU's overall system of legal protection against administrative action? To answer these questions, the volume's first part presents a series of case studies, covering all the EU boards of appeal currently in existence, while a second part looks into the horizontal issues raised by the phenomenon of the boards of appeal.