Abstract
Social Impact Bonds (SIBs) demonstrate the growing interest in innovative financing solutions that seek to address complex social challenges through cross-sector collaboration. This paper reviews experience of implementing SIBs, drawing insights from case studies and interviews to identify the lessons learned that can inform the design and implementation of future SIBs. Our analysis reveals inherent tensions between flexibility and standardization, between stakeholder expectations and outcome attainability, as well as between the context-specific nature of SIBs and the scope for creating a replicable model. A thematic analysis of qualitative data from 30 SIB case studies contributes to the empirical literature on social financing, providing actionable insights for policymakers, investors and service providers engaged in or considering SIBs as a mechanism for social change.