Pay for success (PFS) is a new method of forming public private-partnerships in the US. Private investors finance a social program with a specific performance goal. If an independent evaluator certifies that the program achieves its goals, the investors receive their principal and a return. If the program does not achieve its performance targets (such as recidivism reduction), some or all of the investment is forfeit. The Urban Institute´s report shows that risks associated with social impact bonds can be mitigated by following a five-step model. Source: http://www.urban.org/UploadedPDF/413148-Five-Steps-to-Pay-for-Success.pdf