To avoid confusion on the arbitrary distinction between these terms, we will adopt the more commonly applied term ‘third sector organisation’ to denote any such organisation [7, 12].The third sector is often considered to entail distinct features and characteristics in its service delivery compared to public and private sector bodies [2,3,4,5, 13].To identify and synthesise existing research on what barriers and facilitators influence the implementation process of TSOs delivering EBIs.
The third sector is becoming a growing provider of public, social, and health services.
However, there is little evidence on the effectiveness of third sector organisations (TSOs), and their capacity to implement evidence-based interventions (EBIs).
Included studies were synthesised using thematic analysis and were quality appraised.
Thirty-one studies were included, most of which were conducted in North America.
For instance, TSOs are thought by some to be better at connecting with hard-to-reach populations, while also being driven by more altruistic values [5, 14, 15].
These perceived traits often appear in the discourse of policymakers, who continue to emphasise the growing importance of the third sector, especially in the context of alleviating social problems [3, 16,17,18,19].However, little research demonstrates evidence on the effectiveness and impact of third sector service deliveries [2, 3, 5, 6].While scholars struggle to agree on a universally applicable definition of the third sector [7, 8], most follow , who point to five characterising traits of third sector organisations (TSOs), i.e.These findings generalise across the included studies and are robust to study quality assessment.While it is often assumed that good outcomes follow when implementing interventions that have been developed and tested according to best practice, little attention has been paid to how EBIs are best transported, contextualised, and implemented by third sector providers.This systematic review found that TSOs faced considerable challenges in implementing EBIs, which were primarily a lack of support and expertise, and unclear/insufficient guidelines on how to adapt EBIs to different populations.To address these challenges, it is important to engage with central stakeholders, such as funders, researchers, policymakers, and practitioners, to discuss how these needs can be met. The third sector is expanding and becoming a growing provider of public, social, and health services in many high-income countries [1,2,3,4].The failure to understand aspects related to implementation introduces the risk of overlooking type iii errors (‘implementation failure’) [40, 41], i.e.failure to implement an intervention as intended .Overlooking this issue has great implications for policy and practice, as it may lead to false inferences about the effectiveness of interventions and programmes.Thus, without understanding the implementation aspects of third sector service deliveries, it is difficult to assess their potential to substitute for public sector provision of social and health services.