The present study aims to evaluate the legal and institutional strategies affecting the sustainability and efficiency of endowments in Iran and Turkey. Endowments, as institutions with extensive economic, social, and cultural capacities, have faced challenges in recent decades, such as weak management, lack of financial transparency, and inefficient monitoring mechanisms. A comparative study of the two legal systems of Iran and Turkey can help identify the strengths and structural deficiencies in the field of policy-making and governance of endowments. The main issue of the research is to what extent the existing legal and institutional systems in Iran and Turkey have been effective in ensuring the sustainability and promoting the efficiency of endowments. The aim is to comparatively analyze the legal frameworks, institutional structures, and management policies of the two countries and provide a combined model for improving the governance of endowments. The research method is descriptive-analytical with a comparative approach, and data are collected through systematic review of laws, regulations, and official documents, along with content analysis of organizational reports and semi-structured interviews with experts in the field of endowment. The findings show that the Turkish endowment system, with legal reforms and the use of modern financial instruments, has been able to move towards economic sustainability and more effective supervision; while Iran has rich social capital and cultural capacities, it needs institutional modernization, information transparency, and the development of integrated support policies.