This document discusses social impact bonds, which are an innovative financing mechanism. Social impact bonds allow governments and donors to commission social services from impact-driven organizations, which are paid by investors based on outcomes. Nearly 50 social impact bonds are currently operating worldwide, addressing issues like homelessness, health, employment, and recidivism. For social impact bonds to flourish, there needs to be a focus on measuring outcomes, innovation, and cultural shifts toward evidence-based interventions.