"This paper considers approaches towards improving the predictability of aid to low income countries, with a special focus on budget support. In order to accelerate progress towards the Millennium Development Goals, the donor community is increasing aid flows while pushing for more coordination and tighter performance-based selectivity. However, these factors may increase the unpredictability of aid from current levels, which are already high enough to impose significant costs. Predictability is a particular challenge in the area of budget support, which will continue to increase in importance as aid is sought to underpin longer-term recurrent spending commitments. Budget support reduces transactions costs and drains on capacity, but it tends to be more vulnerable to fluctuations than multi-year project support. Poor predictability raises the threat of a low-level equilibrium ... " -- Cover verso.