This programme will pilot Development Impact Bonds (DIB), a new business model for tackling complex social problems in international development by financing programmes on a Payment by Results basis. This work will look at building the evidence for the suitability of DIBs in improving the efficiency and effectiveness of development programmes in areas including income generation, health and disability, by supporting a small number of projects designed by other donors or delivery partners where this financing structure is desirable and feasible. Evidence generated through the pilot will help us to understand when DIBs may be an appropriate commissioning tool, how they can be designed to support providers to innovate and deliver better outcomes, and the costs and benefits of using DIBs.