In this article, we propose a vision of a social impact bond (SIB) model that moves beyond just achieving cost-savings to spurring innovation, knowledge-building, rigorous evaluation, and, potentially, outcomes that go beyond cost savings. We discuss two of the key rationales for SIBs: securing new resources to expand programs more broadly and ensuring that government only pays for successful programs that save money. Both are important goals but are also limited. We therefore propose a more expansive vision of the SIB model.