This research briefing introduces the Capacity Cube framework – a new tool for thinking about how capacity to deliver national social protection programmes and systems might be sustained in times of crisis. Its threedimensional approach is specifically designed to analyse the particular capacities needed to deliver resilient programmes in protracted crises and to identify strategies to address any deficits. This briefing explains the Cube framework and its development and application. An accompanying briefing (Slater 2024) presents early findings using the Cube in Nigeria, Iraq, and Syria.