Assistance to fragile states must be flexible enough to take advantage of windows of opportunity and respond to changing conditions on the ground. At the same time, given low capacity and the extent of the challenges facing fragile states, international engagement may need to be of longer-duration than in other low-income countries. Capacity development in core institutions will normally require an engagement of at least ten years. Since volatility of engagement (not only aid volumes, but also diplomatic engagement and field presence) is potentially destabilising for fragile states, international actors must improve aid predictability in these countries, and ensure mutual consultation and co-ordination prior to any significant changes to aid programming.