In early 2014, NSPCC commissioned the Centre for Child and Family Research (CCFR) at Loughborough University to provide evidence to inform debates about the cost effectiveness and potential long term savings, or costs avoided, of providing appropriate assessment, support and services to families on return home from care (reunification). The aim of the work was to estimate the costs to the public purse if services to support successful reunification are provided to all children and families following a care episode, based on their assessed needs, and to compare these costs with the costs associated with re-entry to care. This report explains the context for focusing on reunification practice, describes the methodology and provides the evidence base used to estimate the costs.