The International Commission of the Red Cross (ICRC) currently registers 100,000 people as missing due to conflict; it acknowledges that number is only a fraction of the real total (ICRC 2018). The scale of the problem of the missing, and the damaging, long-lasting impact on families and communities, creates enormous challenges for societies rebuilding after conflict. There is growing evidence that the responses of international, state and nongovernment (NGO) actors have failed to effectively address these challenges. By narrowly interpreting ‘the missing’ as a human rights problem to be resolved through transitional justice (TJ) mechanisms or an inconvenient political problem to be resolved through bureaucratic control, these responses have overlooked local understandings of the missing. This undermines sustainable peacebuilding, which is predicated on addressing local needs. Through a comparative ethnography of Timor-Leste and Sri Lanka, this project aims to bring local epistemologies, needs and practices in from the margins to the centre of scholarly analysis and practice around missing persons. This will clarify the conditions under which international, state and NGO responses to the missing can more effectively contribute to sustainable peace.