Some decades ago, dissatisfaction with the state of comparative studies in the field of private law induced a group of scholars, in the context of the seminars organized by the Cornell Law School, to elaborate an innovative methodology – a ‘factual analysis’, based on hypothetical cases – in order to ascertain whether among some of the major legal systems of the world there were not only differences, but also some shared and connecting elements; that is, a common core. A research project of this kind, designed to analyse both common and distinctive traits between European administrative laws, was initiated by the author of this article some years ago. The present article, first, explains the purposes to be served by the new comparative research and its subject; that is, administrative procedure, as distinct from judicial review of administrative action. Second, it discusses some issues concerning both the methods employed and the choices made with regard to the legal systems selected. Third, it illustrates the main lines of research developed and their results, both expected and unexpected.