This overarching synthesis brings together the findings of four systematic reviews including 138 studies focused on non-pharmacological interventions for ADHD used in school settings. These reviews considered the effectiveness of school-based interventions for ADHD, attitudes toward and experience of school-based interventions for ADHD, and the experience of ADHD in school settings. We developed novel methods to compare the findings across these reviews inductively and deductively. Key contextual issues that may influence the effectiveness and implementation of interventions include the relationships that pupils with ADHD have with their teachers and peers, the attributions individuals make about the etiology of ADHD, and stigma related to ADHD or intervention attendance. Although we found some positive effects for some outcomes and intervention categories, heterogeneity in effect size estimates and research evidence suggests a range of diverse contextual factors potentially moderate the implementation and effectiveness of school-based interventions for ADHD.