Notes Social Impact Bonds for Health and Social CareSocial Impact Bonds for Health and Social Care OverviewOutcomesOutputs Social Impact Bonds (SIBs) have recently become part of the public services landscape in the UK and internationally. In a SIB contract, public sector commissioners partner with private or Third Sector social investors to fund interventions that seek to tackle complex social issues. Under these arrangements, non-government investors cover the upfront costs necessary to set up the interventions implemented by service providers, while the government commissioner commits to pay a return on investment if pre-defined desired outcomes are reached. In the field of health and social care, nine projects across England, collectively known as the SIB ‘Trailblazers’, have received seed funding from the government’s Social Enterprise Investment Fund to evaluate and potentially implement a SIB. The Department of Health’s Policy Research Programme commissioned an independent evaluation of these projects from PIRU, in partnership with RAND Europe, to explore their potential benefits and costs.