What is the contribution of development cooperation to the 2030 Agenda, and how can accountability for that contribution be ensured? For the policy field of development cooperation, the 2030 Agenda for Sustainable Development means fundamental change that necessitates adjustments to established principles, in particular "mutual accountability", by which two partners agree to be held responsible for the commitments they voluntarily made. The accountability framework for the 2030 Agenda evolves in parallel to the changes in the development cooperation policy field, and there are lessons to be learned. In order for the High-level Political Forum (HLPF) to emerge as the locus of "global accountability", the entry points, channels and feedback loops for the inputs from various stakeholders require further specification. The danger that development cooperation stakeholders do not follow through with their commitments, and are not held accountable, makes exploring accountability crucial.