Indonesia is a plural society characterized by diversity in religion, ethnicity, culture, language, and social background. Such diversity is a national asset, but it may also become a space for prejudice, exclusivism, and intolerance when learners are not equipped with the capacity to respect differences. In this context, Islamic Religious Education (IRE) has a strategic position because it is not merely concerned with transmitting religious knowledge but also with developing students' attitudes and behavior. This study aims to analyze the internalization of tolerance values through IRE learning, the forms of tolerance that can be developed, relevant learning strategies, and supporting and inhibiting factors. This study employs a qualitative descriptive library research method. Data were obtained from scholarly journal articles, books, policy documents, and other relevant academic sources and analyzed through identification, selection, classification, interpretation, and thematic synthesis. The findings indicate that the internalization of tolerance in IRE can be developed through three main stages: introducing and understanding values, habituating and experiencing values, and practicing values in social behavior. Relevant values include tasamuh, justice, respect for differences, deliberation, balance, and social responsibility. Effective strategies include dialogical learning, case discussions, contextual learning, cooperative learning, teacher modelling, and the creation of an inclusive school culture. Internalization will not be optimal if it stops at the delivery of concepts; tolerance values need to be manifested in teacher-student interaction, learning methods, assessment of attitudes, and school culture. Therefore, IRE can serve as an important instrument for developing students who are religious while also being open-minded, fair, and capable of living harmoniously in a plural society.