<![CDATA[This study aims to trace the history and dynamics of mosques and langgar (small prayer houses) as Islamic educational institutions in the Indonesian archipelago, and to explain how they have endured and succeeded in fulfilling their educational function amid changing times. The research employed a qualitative approach combining historical methods with field study. Data were collected through in-depth interviews, observation, and documentation, then analyzed through heuristics, source criticism, interpretation, and historiography, as well as data reduction, display, and conclusion drawing, with data validity maintained through triangulation. The results show that the mosque was the earliest Islamic educational institution, while the langgar emerged as an elementary-level place of learning covering Qur’anic recitation, worship procedures, and moral education. Both institutions shifted into the foundation of basic religious education once pesantren, madrasah, and modern schools appeared. The findings indicate that the success of mosques and langgar is sustained by close social ties with residents, community-funded operations, natural regeneration from former students, the integration of learning with local religious traditions, and gradual adaptation without abandoning core values. Thus, the socio-cultural strength of the community determines the success of traditional Islamic educational institutions, so efforts to strengthen them should preserve this strength, in line with the Sustainable Development Goals (SDGs).]]>
