This study aimed to describe "nyantri" (Islamic crash course) program as a leadership strategy adopted by school principals in strengthening the school organizational culture. This study used a qualitative approach via theoretical phenomenology orientation and a multicase design. The data collection was done through observation, documentation, and in-depth interviews. The validity of the data was measured by data reduction, data presentation, and conclusion. The results of this study found three models of Islamic crash course performed: "tashih," that is, "Al-Qur'an" reading competence, "taushiyah" (Islamic lecture) of leadership values, and apprenticeship for the application of a "santri"'s (Islamic crash course student) character values. The benefits for the teachers are the preservation of their "Al-Qur'an" reading competence and the improved intensity of the leadership and application of Islamic values, which form the school organizational culture. An integration of values rooted from the three models into the institutional vision could strengthen the school organizational culture to improve school achievement.