Authors: Bronwen Maxwell, Bernadette Stiell, Anna Stevens, Sean Demack, Mike Coldwell, Claire Wolstenholme, and Sarah Reaney-Wood (Sheffield Institute of Education, Sheffield Hallam University) and Hugues Lortie-Forgues (University of York).

The aim of this review was to support EEF, other funders, developers and deliverers scaling-up interventions, by comparing effect sizes at the efficiency and effectiveness stages for the EEF effectiveness trials that had been completed by 2019 and conducting a qualitative analyses of interviews with developers and deliverers who have been engaged in scale up from an EEF efficacy trial to an effectiveness trial. The review discusses approaches and programme features that either support or hinder intervention scale-up to large numbers of schools.