Background: The importance of a strategic approach to the prevention of suicidal behaviour, grounded firmly in research evidence of interventions that mitigate or counteract risk factors and enhance protective factors, has long been recognised. The identification (and, subsequently, implementation) of effective interventions (examples include: restrictions on access to commonly used methods of suicide; media suicide reporting guidelines; school-based programmes; postvention; and psychotherapeutic interventions) remains a major challenge. Unfortunately, the existing evidence base is incomplete and lacks authoritative synthesis. We have conducted an umbrella systematic review, focusing on systematic review-level evidence for each intervention, with a view to filling this crucial knowledge gap. Methods: This umbrella review, focusing on systematic review-level evidence for each intervention, was informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and used the AMSTAR-2 critical appraisal tool to rate the quality of included reviews. Twelve databases were searched for relevant literature published in any language during 2002-2022. The effectiveness of interventions on suicide-related outcomes (suicide, attempted suicide/suicide attempt, suicidal behaviour, and self-harm) was assessed using narrative synthesis. Findings: A total of 5271 citations was generated from which 140 reviews in scope were identified. Findings reported below are restricted to 89 reviews of high and moderate quality. Based on preliminary analysis, we find strongly supportive evidence for: structural interventions that restrict access to tall buildings and bridges and in some railway settings; restriction of access to pesticides; cognitive behavioural therapy for adults; dialectical behavioural therapy for children and adolescents; and enhanced care, including safety planning. There was weakly supportive evidence for community interventions, interventions in settings such as schools and prisons, substance misuse programmes, screening of children and adolescents attending emergency departments, pharmacological interventions (lithium, ketamine), mentalisation behavioural therapy and brief interventions. For other interventions there was limited and or conflicting evidence. The definitive findings, based on the complete analysis, will be reported at the conference. Conclusion: The findings of this review add to our knowledge about effective interventions to be considered for inclusion in national suicide prevention strategies. However, due to methodological limitations (relating to both systematic reviews and the primary studies on which they rely) and a failure to explore key topics (e.g., whether effectiveness varies by socio-cultural or socio-economic characteristics at aggregate or individual level), our evidence base remains uneven and in need of further sustained investment.