This chapter critically examines the paradox of persistent underdevelopment in the Bangsamoro despite decades of foreign aid development programs following formal peace agreements. By comparing two major post-conflict development aid interventions, the UN/Multi-Donor Program and the Mindanao Trust Fund-Reconstruction and Development Project (MTF-RDP), this chapter explores the structural limitations of aid in promoting sustainable peace and inclusive development in the Bangsamoro. Using qualitative methods, including key informant interviews, focus group discussions, and document analysis, the study identifies four key challenges: donor-driven priorities, lack of local ownership and participation, mismanagement and misallocation of resources, and the destabilizing presence of rido (clan-based conflict). Grounded in dependency theory, the study conceptualizes the Bangsamoro as an internal periphery within a peripheral state, where externally designed aid frameworks reproduce structural inequalities. The lack of sustainability planning and exit strategies contributed to the deterioration of aid outcomes over time. Rather than delivering the promised peace dividends, these programs often reinforced aid dependency and deepened marginalization. The chapter calls for a fundamental rethinking of development aid, one that centers local participation, conflict sensitivity, and long-term institutional capacity, to achieve inclusive and sustainable peace in the post-conflict context of Bangsamoro.