The study examines the intellectual heritage of Transylvanian Calvinism, analysing the formation of the library collection of the Protestant Theological Institute in Cluj. As the sole documentation institution for Hungarian Protestant pastoral training in Transylvania, it represents a unique cultural legacy. The library served as an essential component of Calvinist ministerial and theological education in Transylvania. The creation of the collection was influenced by financial constraints, and its growth was determined by the annual budget, community support, and donations. The library reflected a demand for modernization and played a crucial role in elevating the cultural literacy of the Transylvanian society. The study highlights the organizational structure of the library, the leadership roles of Szász Domokos and Pokoly József, and the library’s societal responsibility in preserving and disseminating knowledge. Keywords: Transylvania, Cluj, 19th century, Calvinist church history, school history, pastoral training, library history, library foundation (1895), library development, acquisitions, donations, Domokos Szász, József Pokoly