The text corpus collects the reformation related protocol records of Debrecen’s magistrate from the time between 1551 and 1685. The exact start date of the reformation in Debrecen is unknown, however, it certainly took its roots during the times of reformer Márton Kálmáncsehi Sánta in the 1550’s. Péter Méliusz Juhász had the most important role in the consolidation of the reformed religion. His work was supported by the rapidly spreading printing press and the reformed school, which served the propagation of Calvinism even more vividly. The organizational and doctrinal establishment of the reformed church ended by the Reformed Constitutional Synod in 1567 in Debrecen, where the Second Helvetic Confession was adopted. From this time on, Debrecen has become the main hub of Hungarian Calvinism. The change in the life of the city came when Debrecen acquired the free royal city status. The prerequisite of this was the admission of Catholics to the completely Hungarian, reformed city population. As a reply to the actions of the government and the church, the inhabitants of Debrecen responded with forceful adherence to the traditions of the civic city – which is also referred to as „Debreceniség”. The herein published sources show the most importantmoments of this process, and we can get an insight into the everyday life of Debrecen’s inhabitants.