Due to rapid population growth, urbanization, and evolving lifestyle patterns, waste management has become one of the most critical environmental challenges confronting Iranian cities. Among the most effective strategies to address this issue is the implementation of source separation, which can significantly contribute to pollution reduction, enhance recycling efficiency, and improve the overall performance of municipal waste management systems. This study adopts a problem-oriented approach to investigate the underlying causes of the limited success of source separation programs in various cities in Iran. It also seeks to propose macro-level strategies to overcome these obstacles. The research methodology is based on a combination of literature review, document analysis, expert interviews, and field studies. Findings indicate that the barriers to effective implementation fall into five main categories: technical and infrastructural, educational, economic, legal, and institutional. Key challenges include the lack of sufficient recycling drop-off centers, inefficiencies in collection systems, absence of continuous public education, weak regulatory enforcement, and overlapping responsibilities among involved institutions. Moreover, international best practices—such as those from Germany, South Korea, and Slovenia—highlight the importance of incentive-based policies like Pay-As-You-Throw (PAYT), targeted public education, citizen engagement, and institutional coordination as prerequisites for successful source separation programs. This study highlights the urgent need for infrastructure revision, the application of economic instruments, increased public awareness efforts, and the development of coherent and transparent legal frameworks to support the effective integration of source separation within Iran’s municipal waste management systems.