The author has taken into consideration three sources that allowed him to trace the missionary activities of the Church in the 10th century. These are: instructions of the Holy See, the royal legislation referring to the ecclesiastical life in the converted country, and local practices and personal initiative of particular missionaries. The instructions and practice of the Roman Church played the most important part. The missionary practice started to take form since the pontificate of Pope Gregory the Great (590—604), which was the result of the demand following the initiative to Christianize England. We learn about this practice in detail, analyzing the papal instructions to St. Augustine. Gregory the Great's instructions were binding in the following centuries as well, especially during the pontificate of Nicholas I (858—867). This found its expression in the famous Responsa Nicolai Papae ad consulta Bulgarorumof 13th November 866. This instruction is particulary important for us because it refers to the Slavonic mission and comes only one century before the Christianization of Poland. We know Responsafrom a copywritten in Rome at the turn of the tenth century, i.e. at the time of the christening of Poland. The activities of Pope John XIII, who patronized the christening and the formation of the ecclesiastical organization in Poland, show the tendency to stress the priority of the Holy See and her authority over all local churches. Although we have no written records referring to the papal mission in Poland, it its only natural to assume on the basis of the common practice of the Church that Poland could not be an exception in this case. So Jordan should be regarded as head of such a papal mission in Poland. In this context the author points out to the reformist synod in Ravenna, in 967. Among the participants of the synod there isa mysterious bishop, called „Joannes episcopus Jordanensis”. Since there is no bishopric of such a name among those listed in the catalogues known to us, the author puts forward a hypothesis about a copyist’s error and cautiously claims that „Jordanensis” may mean the second name of that bishop „Joannes Jordanus”. Perhaps thatsynod, which was concerned with the problem of the mission and ecclesiastical organization among the Polabian Slavs, also dealt with the forming of a missionary group for Poland. So Jordan, who could have been consecrated in Rome at the beginning of 967, took part in the synod in April of the same year, and in 968 he arrived in Poland. In compliance with the papal instructions, the Christianizing Mission in Poland was educational and persuasive, abstaining from force.Martyrs are not heard of in Poland. St. Bruno and St. Adalbert were tortured to death not by Poles, and the Five Brothers were killed by robbers, their missionary work providing no cause for their death.Sources do not say anything that would suggest the bloody conversion of the pagans. The information referring to the monks of Międzyrzecz also testifies to the fact that the local missionaries adapted themselves to local customs, as et was recommended by the Roman instructions.The content of the missionary catechesis in Poland in the 10th century is not known from written sources. For this reason the author makes use of the later example — that of the mission linked with the Church and the Polish State, which was Otto’s mission in Western Pomerania in the second decade of the 12th century. Both Pope Gregory the Great and Nicholas the Great appealed to the monarchs of the countries that were being converted, to support the missionary work of the Church. Answering those appeals the rulers on the territory embraced by Western Christianity in the 10th and 11th centuries used to publish the so called „leges ecclesiasticaeto support the activity of the Church. According to the information recorded by Thietmar and Gallus Anonymous, also Bolesław the Braveissued the „leges ecclesiasticae”. They referred to the ecclesiatical life and discipline, obedience to bishops and priests, security of the Church property and jurisdiction for the clergy. The formation of the Church organization on the Polish territory undoubtedly followed the directions of the Holy See, since there is no evidence that a different model of ecclesiastical organization had been introduced here. So in 968 John XIII, in consultation with Mieszko I, set up a regular bishopric in Poland, with Poznań as its residence, and the first bishop there was Jordan. Rome must have participated directly in setting up to framework of the Polish ecclesiastical organization; one of the indications of this fact was the invocation of the Poznań cathedral, dedicated to St. Peter. According to Thietmar, this Polish diocese covered the whole state of Mieszko I. As time went on Rome started organizing a normal metropolitan network,with the archbishopric in Gniezno.