This is an excellent introduction for anyone looking for information about social impact bonds (SIBs). “As publicly-funded programs and services across the country are experiencing budgetary constraints, many are beginning to look to social impact bonds (SIBs), also known as pay-for-success bonds or social innovation financing, as a possible solution. Under the SIB model, public, private, and nonprofit sectors collaborate to achieve cost savings and improve social outcomes in areas such as criminal justice, juvenile justice, education, foster care, and homelessness. In this innovative model, four entities-a government agency, a private investor, a public or nonprofit service provider, and an intermediary organization-work closely together to implement an SIB bond project, and to support the development, implementation, or enhancement of a social program. Private investors provide funding in the form of a bond to a service provider that delivers social services to the targeted population” (p. 1). This article covers: how a SIB pays for itself; SIB history; U.S. federal support for SIBs; success of SIBs in the United Kingdom; and SIB pros and cons. Included is a great set of links to additional resources about SIBs.