In 2011, Essex County Council’s (ECC) children’s social care service was in serious need of reform, having received multiple ‘inadequate’ ratings from Ofsted, the UK regulator. To improve its effectiveness, ECC hoped to introduce new preventative measures to keep children out of care and at home with their families when it was safe to do so. But amid public-funding cutbacks, ECC had severely limited resources to trial new approaches.

In light of these constraints, ECC was considering an alternative funding model called a social impact bond (SIB): private investors would fund a new intervention upfront, and ECC would repay the investors (plus a return) only if the intervention achieved specified, pre-agreed social outcomes. Specifically, a proposal from a social investment organisation suggested that a SIB could fund Multisystemic Therapy (MST), a licensed, evidence-based programme designed in the US to help at-risk youth remain at home with their families. The ECC had to assess the mixed evidence available on the effectiveness of MST, and consider the trade-offs of using a SIB, which had not yet been used in children’s social care nor at the local-authority level.