The history of the councils permits the recognition of four traditional types of Oecumenical Council - the Old-christian Bishops' Council, which was convened by the Emperor and decided questions of dogma and disci­ pline; the Papal General Council of the middle ages, which was convened, guided and confirmed by the Pope and which, both by reason of the sub­ jects to be dealt with and the personal constitution thereof, represented Christendom; the councils of the 15th century claimed to act as Church Par­ liaments; the Council of Trient, which again reverted to the twO first types and to which the first Vatican Council was similar as to structure, was con­ forming in essentials to the Codex Juris Canonici. Does the present Vatican Council II, as to its structure, show new ten­ deneies which go beyond the characteristics of the historie types? The author believes that five such tendencies can be recognised: 1. The careful preparation by experts, which also include Bishops, due to the predominant influence of the central cu rial authorities extends far beyond that of the Vaticanum I; 2. The consciousness of the collegial joint responsibility of the episcopate, which however 3. co-operates with the Papal primatial authority and which elevates the long contested question of powers into the sphere of responsibility; 4. the pastoral and 5. the oecumenical direction, both of which have been basing on the person­ al initiative of Pope Johannes XXIII.