Pesantren has a distinctive Islamic scientific tradition, namely the kitab kuning tradition. However, now a phenomenon exists where kitab kuning is no longer used. This study aimed to explore changes in the habit of Islamic studies at Pesantren Assalaam. This research used a case study qualitative research at Pesantren Assalaam, Sukoharjo, Indonesia. There were 18 respondents consisting of 10 teachers, 4 pesantren administrators and 4 employees. Observations, interviews, and documentation are used to collect data. The main findings of this study revealed that modernization led to a change in the tradition of Islamic studies, which was marked by the absence of kitab kuning in the pesantren curriculum as a learning reference authority. ...