This brief examines the evidence for how impact bonds affect the larger ecosystem of social service delivery and financing. The influence of impact bonds as a mechanism is considered, independent of the targeted outcomes achieved by the impact bond interventions themselves.

Seven types of ecosystem effects are reviewed: whether impact bonds build a culture of monitoring and evaluation, drive performance management, foster innovation in delivery, crowd in private capital, reduce government risk, incentivise collaboration, and/or sustain impact in social service delivery ecosystems.

Qualitative evaluations of completed impact bonds and interviews with impact bond stakeholders in active and completed deals show that impact bonds do seem to influence the systems where they are active by shifting mindsets and building stakeholder capacity.