This policy brief outlines a research agenda for differentiated ART delivery based on a think tank discussion convened by the Differentiated Service Delivery (DSD) initiative of the International AIDS Society that brought together key stakeholders from eight countries, including ministries of health, HIV service providers and HIV implementation scientists. The research gaps identified from the discussion are presented in this brief, arranged according to the four groups of people living with HIV as described by the World Health Organization. The brief is available in English, Portuguese and French language.