Social Finance is a not for profit organisation that brings together finance, social and governmental expertise to redesign public services. Where necessary we help to bring in social investors who can provide finance and take on delivery risks to enable the implementation of innovative new models. Since late 2007 when we started to develop the Social Impact Bond (SIB) idea, we have worked with HM Treasury, Ministry of Justice, the Department for Communities and Local Government, Home Office, Department for Work and Pensions, Cabinet Office and a variety of local authorities to assess and create models in different issue areas. This guide draws on our experience to date in exploring the feasibility of SIBs, particularly in the area of Children’s Services. Social Finance worked with Essex County Council to develop and launch the first local authority-commissioned SIB in November 2012. The Essex SIB focuses on vulnerable adolescents at the edge of care or custody and funds intensive intervention in order to reduce the time they spend in care or custody and enable them to stay “safely” at home with their families if possible.