Scientists assess and interpret the content and essence of the process of societal modernization in different ways; however, the issue of equal opportunities undoubtedly constitutes an element of the modernization process, even though it may also be examined within a broader postmodern or human rights context. The issue of equal opportunities is frequently analyzed in sociology as an integral part of the process of societal modernization. Classical theories of modernization associate modernization with processes of rationalization, individualization, and social differentiation, which weaken traditional hierarchies and strengthen formal equality (Weber, 1978; Durkheim, 1984). In this context, the principle of equal opportunities functions as a structural mechanism for regulating social inequality and ensuring that individuals' social positions are based on achievements rather than inherited characteristics. In our view, such processes of societal modernization in seventeenth-century Lithuania and throughout the Eastern European region were influenced by the scholarly works and activities of Jan Gruzewski. Serving as Rector of Vilnius University in 1618-1625 and 1641-1643, and as preacher to King Sigismund Vasa of the Polish-Lithuanian Commonwealth from 1626 to 1630, he actively contributed to academic and public life and, in 1644, established the Faculty of Law at Vilnius University. In his public activities, although he was a Jesuit, he was known for his tolerance toward adherents of other faiths and for promoting interreligious dialogue. Research into J. Gruzewski's academic works (none of his works have been translated from Latin to date) and activities will allow us to more fully reveal his influence on the processes of societal modernization in this part of Europe.