Three and a half centuries have passed since Fr. Johannes Bolandus (1596-1665) when the publishers of Acta Sanctorum, who were called the Bollandists, took upon themselves the responsibility for publishing the lives of the saints. After Roswade’s death, Bolandus modified the original project thus setting an authoritative Bollandist methodology. His most significant contribution was in a fact that had taken into consideration not only such reports on the saints which were contained in the official lives of the saints, but also those which were just given mention in other works, or those which were known from short biographic notes, from their feast days which were recorded in the martyria, on monuments, or in their popular celebrations. The most significant principle of Bolandus and Henschenius was that they extended equal significance both to non-literary and literary records, and obvious non-historic, legendary sources which deserved to be taken into consideration. It is a difficult task to clarify Bollandists’ methodology. In describing the subject of hagiographic methodology, the presentation moves in three directions. The appropriate subject of hagiography, as the very word points out, is the hagios, the saint, the person who is being celebrated by Christians for his heroic example of Christian life. The saint differs from any other historical personality, by becoming significant especially so from the day of his death (in case of a martyr), or through events during the last days of his life (in case of other saints). Investigation of evidence relies on documents which testify on the existence of sainthood and on those that relate to martyrdom, to saint’s life, indicating miracles which hade occurred during the life of the saint and after his death. Genuine historical work begins with the study and interpretation of existing evidence. The last methodological principle used in the conclusion of a work, strives to penetrate the general state of human consciousness through history in general, and especially so in hagiography: a healthy critique is being recommended, equally pointed against conservatism and hypercriticism.