Beyond the SIB Hype: What does the evidence show us? A systematic review of empirical research on Social Impact Bonds.

Antonio Manzi (*)


Seven years have passed since the launch of the first Social Impact Bond (SIB), a relatively new funding mechanism to finance the delivery of social services with private investments. The basic structure of these schemes consist of a specific social issue identified by the government and a non-governmental service provider is selected to implement an intervention to address that issue, while funds are secured from private sector investors to finance the cost of the program. After a predefined period, an evaluation concludes if the program achieved the predetermined social outcomes. If it does, the government pays back the investors plus a return. If it doesn´t, then the government does not pay, and the investors either lose their money, or, in some cases, a philanthropic donor or other institution underwrites the investment. As of July 2017, more than 85 SIBs have been launched in 18 countries, and many more are in development.

Discussions surrounding SIBs have seen proponents and detractors pointing at their potential benefits and dangers, given that only a few SIBs have been implemented for enough time to be evaluated. In theory, SIBs promise to provide a solution for cash-strapped governments who are struggling to solve entrenched social problems by financing non-governmental service providers with external investments to deliver innovative and measurable solutions to these problems. However, some cautionary voices, especially from academia, point to a potential subjugation of private values over public ones, a marketization of social issues, and a government retreat from its social responsibilities.

My Master´s dissertation* contributes to the discussion by analysing and comparing recent empirical research against ten common claims about SIBs. Using a framework systematic review, 24 studies – comprising independent evaluations, academic studies, and investor and intermediary reports – were selected and analysed. Findings suggest that six of these claims – that SIBs prioritize prevention, focus on outcomes (instead of traditional inputs or processes), shift risk away from public sector, drive performance management, foster a culture of monitoring and evaluation, and stimulate collaboration – have evidence to support them. For others – that SIBs foster innovation in service delivery, can help achieve scale, sustain impact and bring additional funding from private sector – evidence is unclear or it is too soon to be determined.

As more countries and organizations begin exploring and promoting SIBs, looking beyond the purported benefits and focusing on the early evidence of the performance of these mechanisms is of vital importance.


*Chevening Scholar, MSc. (c) Public Policy and Management, King´s College London. For the full study, please contact Antonio at