ENThe paper analyzes the community of the Lithuanian province of the Society of Jesus between 1608 and 1773. It adopts a prosopographical approach based on the full set of the order’s personnel catalogs for the Lithuanian and Masovian provinces, which have been analyzed by means of R Studio, an integrated development environment based on the R programming language. The author focuses on the total number of Jesuits in the province, their religious or secular status, final vows, education, regional distribution, and geographic origin. In the long term, changes mainly depended on local factors such as the cultural assimilation of the inhabitants of the eastern territories marked by the influence of the Orthodox Church. In the short term, wars and epidemics also played an important role. However, some of the trends in the Lithuanian province, such as the number of professed of the four vows, which increased due to the larger availability of theological courses during religious formation, were similar to those in other administrative units of the Society. Overall, the article demonstrates that the seventeenth-century crises had a profound impact on the Jesuit community both in terms of numbers and internal structure. Keywords: Jesuit prosopography; Polish–Lithuanian Commonwealth; Grand Duchy of Lithuania; lay brothers; fourth vow; geographic origin. [From the publication]