The Addis Ababa Action Agenda raises the urgency to address growing financing and capacity needs at all levels of government in developing countries (para. 34) while the 2030 Agenda calls to “localise” the SDGs. In its High Level Communiqué of 31 October 2017, the DAC stressed that “complex challenges increasingly require coherent approaches at all levels and co-ordinated, inclusive actions”, remaining “committed to improving quality and impact of our development co-operation policies”. Decentralised development co-operation, or international development co-operation carried out by subnational governments, is one tool OECD Development Assistance Committee (DAC) members can deploy to ensure that development co-operation is fit-for-purpose and responds to the local realities of the 2030 Agenda. The paper provides an assessment of the potential strengthens of decentralised development co-operation approaches as well as new opportunities to overcome longstanding challenges, including through the promotion of new forms of multi-level and multi-stakeholder partnerships.