When discussing the composition of the Polish and Lithuanian provinces of the Society of Jesus, this article is part of the trend of prosopographic and socio-historical research devoted to the clergy of the Roman Catholic Church. The aim of the research is to grasp both permanent elements and changes that took place in the structure of the Jesuit community in the Polish-Lithuanian Commonwealth. The author not only presents similarities and differences in the development of the Polish and Lithuanian provinces, but also discusses the trends occurring in their area in a wide pan-European context, comparing the situation of Polish and Lithuanian Jesuits with other administrative units of the order. The chronological scope of the work covers the years 1608–1773, i.e. from the creation of the Lithuanian province as a result of the division of the Polish administrative unit of the order to the dissolution of the Society. The base of primary sources consists of annual and three-year catalogues kept in the Roman Archives of the Society of Jesus, which were analyzed in the form of survey using statistical methods. Against the background of the development of the institution’s network and its financial situation, the author focuses on four issues: the number of Jesuits, their religious vows, their geographical distribution and regions of origin. The conducted research above all shows the influence of the political and military situation of the state on the size of the Jesuit community: the wars of the mid-17th century and, albeit to a lesser extent, the first decade of the 18th century brought serious consequences. The structure of the community in terms of religious vows evolved in a similar way to other European provinces of the Society, as indicated by the increase in the number of professes of four religious vows, who constituted the elite of the order. This phenomenon testifies to the fact that, despite the crises that affected the Commonwealth, the order provided its members with better and better education. The geographical distribution and regions of origin of the Jesuits are closely related, since the recruitment of candidates for the order took place mostly among graduates of Jesuit schools. The most important change in this respect was the increase in the significance of the eastern territories of the Commonwealth both in terms of the number of friars residing there and the participation of representatives of local society in the Jesuit community. As a result of this tendency, in the 18th century the role of the inhabitants of the ethnically Polish territories of the Commonwealth weakened; in the previous century they had constituted, due to their geographical mobility, a substantial part of the Jesuit community in the eastern regions of the Polish-Lithuanian state. This phenomenon clearly indicates the process of cultural integration that took place in the eastern lands of the Polish-Lithuanian Commonwealth, and changes in the social mechanism of recruiting friars, manifested in the increase in the number of Jesuits of noble origin.