Alternative dispute resolution (ADR) is a topic that most think they know about, but in reality, it has multiple facets that cannot be gauged so easily. The concept of ADR applied to public law increases the complexity of the debate. The book attempts for the first time to do a comparative assessment of the state of the art of the ADR in administrative law of several European jurisdictions and at the level of European Union law. It then tries to analyze both empirically and comparatively, also for the first time, the effectiveness of selected ADR tools employed by the different administrative justice systems—namely, administrative appeals, ombudsman, and mediation. Administrative appeals have always been considered an affordable tool for ADR in administrative matters, and a way of keeping litigations out of the courts. Nevertheless, the two systems of administrative appeals have fuelled debates concerning their efficiency, effectiveness, access to justice, promotion of good governance principles and accountability, in relation to mediation procedures. The Council of Europe’s Committee of Ministers has stressed repeatedly, in its recommendations, the idea that alternative means of solving administrative disputes are commendable because of their role in reducing the caseload of the courts while still securing a fair access to justice. It was also pointed out that the courts’ procedures in practice may not always be the most appropriate to resolve administrative disputes, and that the widespread use of alternative means of resolving administrative disputes can allow these problems to be dealt with and can bring administrative authorities closer to the public. However, in the comparative literature, it seems that there is no empirical research measuring the effectiveness of administrative appeals and other ADR tools. The few writings that tangentially touch upon the issue of administrative appeals are mostly descriptive, some even out of date, and they do not address its influence on the judicial review and its effectiveness as an ADR tool.