Madrasa are Islamic educational institutions oriented towards Islamic learning and general science in an integrated manner. The Madrasa curriculum is designed so that students can study Islamic religious knowledge in depth and general knowledge like schools in general. In boarding school-based madrasas, the madrasa curriculum is integrated with the boarding school curriculum with a more comprehensive deepening of Islamic religious knowledge. The boarding school curriculum that has been integrated provides religious education content, moral education experiences, school, and general education, as well as skills that need to be managed with integrative management. This study aimed to describe the planning of the boarding school-based madrasa core curriculum and identify the forms of boarding school-based madrasa core curriculum assessment. This type of qualitative research with a multi-site approach, namely, research focused on explaining or disclosing differences from different sites and occurs in different research arenas. This descriptive research aims to obtain an in-depth description of core curriculum management in Islamic boarding schools, namely MTsN 2. Data collection techniques used include (1) in-depth interviews, (2) participant observation (participant observation), and (3) study documents (study documents). Data analysis techniques in multi-site studies were carried out in two stages, namely: (1) analysis of individual site data (individual cases); and (2) cross-site data analysis (cross-cases analysis). The study’s findings explain that the core curriculum for Islamic boarding schools is formulated and developed by focusing on students’ potential, development, needs, interests, and environment.