Social Impact Bonds are a new form of cross-sectoral collaboration which attracts private financial investment to social programs by offering to pay a market rate of return should the intervention meet its predefined targets. SIBs monetize the benefits of social interventions and tie pay to performance. Ideally they transfer risk from the public sector to private sector investors and attract new funding to social interventions. Drawing from theory regarding contracting, marketization, performance evaluation and taking lessons from experience with public private partnerships in physical infrastructure, this paper explores the public values at stake in the SIB innovation. Using a focus on actors, processes and outcomes, the paper outlines the opportunities and concerns SIBs present for public administration scholars concerned with public value creation and preservation.