PurposeThe purpose of this paper is to explore the wider context in which the national evaluation of the Adoption Support Fund (ASF) was delivered and raise concerns about the sustainability of the early outcomes.Design/methodology/approachThe paper briefly summarises the outcomes of a two-year mixed-methods evaluation. This included a two-wave postal survey (n=792) and follow-up (n=481), an online survey of adopters (n=586) and professionals (providers n=50, local authority staff n=124) and in-depth family interviews. The focus of the discussion on sustainability is drawn from the qualitative research of 10 local authority case studies based on 86 interviews with adoption teams and 33 providers and the perspectives of parents.FindingsWhilst the ASF showed modest early outcomes for families in terms of improved mental health and wellbeing without the scaffolding of wider support of services able to understand the complex lifelong needs of adoptive children and their families, the sustainability of the benefits of therapeutic support is questioned. Adoption teams struggled with the increased burden of administration of the fund, their knowledge of therapeutic interventions, an evidence base and quality of provision from a market that is difficult to regulate. In a society that is failing to meet the mental health and wellbeing needs of children generally, how can a single intervention meet the needs of a very vulnerable group?Research limitations/implicationsResearch and evaluation on interventions in children’s social care could be more systems aware and instead of narrowly focusing on outcomes pay attention to the complex network of services that interlink to support vulnerable children and their families and the restraints on resources that they are working with.Social implicationsTo prevent adoption breakdown and increase recruitment of adopters, support for adoptive families needs to be improved beyond the current scope of the ASF. A wide range of services are required to support adopted children particularly as they grow into adolescence. While families have the right to live independently of social services, the awareness of their needs throughout public organisations should be raised particularly in schools.Originality/valueThis paper represents the views of the evaluators at TIHR of the ASF beyond the scope of the original evaluation. It reflects on the wider context of the role out of the Fund and raises important questions about the failure to support the mental health and wellbeing needs of the most vulnerable children in society. It is an organisation reflection drawing on early research in children’s social care from its archive.