Mental disorders are a global health problem. In 2019, 1 in every 8 people, or 970 million people around the world were living with a mental disorder (The Institute for Health Metrics and Evaluation, 2023). Several treatments are available for mental disorders, with pharmacotherapy and psychotherapy as first line treatments. However, effect sizes of psychotherapies and pharmacotherapies for mental disorders are limited (Leichsenring et al. 2022). Preventing the onset of mental disorders and promoting mental health could be an additional method to reduce the disease burden. Over the past 20 years, mental health care has experienced a major technological revolution in that interventions are increasingly delivered via the Internet (Andersson et al. 2019). The digital delivery of mental health interventions has two remarkable advantages. First, digital interventions are highly scalable, as they can help many people at once. Second, digital interventions, compared to face-to-face contact, can be more resilient in the face of crises due to their independence from human contact. For example, participation at prevention courses offered by the public health care in Germany decreased by 44% between 2019 and 2021, which is attributable to the COVID-19 pandemic (Schempp & Römer, 2022). The body of primary intervention-studies on the effectiveness of digital mental health interventions is large, as well as the number of systematic reviews (SRs) and meta-analyses (MAs) that synthesize the evidence of the interventions' effects. Meta-analytic evidence shows the effectiveness of digital interventions for the prevention of depression (e.g., Reins et al. 2021, Sander et al. 2016, Deady et al. 2017), anxiety (e.g., Spijkerman et al., 2016), and suicide (e.g., Büscher et al., 2020), for the reduction of perceived stress levels (e.g, Heber et al. 2017), sleep problems (e.g., Soh et al., 2020), and alcohol consumption (e.g., Riper et al., 2018), as well as for the promotion of well-being (e.g., Ferrari et al., 2022) and resilience (e.g., Ang et al., 2022). Umbrella reviews, or, in other words, overviews of reviews, allow for a bird's eye view on a subtantial body of evidence and its quality (Ioannidis et al., 2017), typically for both beneficial and adverse outcomes (Aromataris et al., 2015). To our knowledge, no umbrella review has evaluated the effectiveness of different types of digital mental health interventions to prevent mental disorders and to promote mental health. The objective of this umbrella review and meta-analysis is to close this research gap by encompassing both an umbrella review (of systematic reviews and meta-analyses) and a meta-analysis (of individual studies) including various mental health conditions and intervention types (e.g., psychological, physical activity, web-based, app-based). Ang, W. H. D., Chew, H. S. J., Dong, J., Yi, H., Mahendren, R., & Lau, Y. (2022). Digital training for building resilience: Systematic review, meta-analysis, and meta-regression. Stress and Health, 38(5), 848–869. https://doi.org/10.1002/smi.3154 Andersson, G., Carlbring, P., Titov, N., & Lindefors, N. (2019). Internet Interventions for Adults with Anxiety and Mood Disorders: A Narrative Umbrella Review of Recent Meta-Analyses. The Canadian Journal of Psychiatry, 64(7), 465–470. https://doi.org/10.1177/0706743719839381 Aromataris, E., Fernandez, R., Godfrey, C. M., Holly, C., Khalil, H., & Tungpunkom, P. (2015). Summarizing systematic reviews: Methodological development, conduct and reporting of an umbrella review approach. International Journal of Evidence-Based Healthcare, 13(3), 132–140. https://doi.org/10.1097/XEB.0000000000000055 Büscher, R., Torok, M., Terhorst, Y., & Sander, L. (2020). Internet-Based Cognitive Behavioral Therapy to Reduce Suicidal Ideation: A Systematic Review and Meta-analysis. JAMA Network Open, 3(4), e203933. https://doi.org/10.1001/jamanetworkopen.2020.3933 Deady, M., Choi, I., Calvo, R. A., Glozier, N., Christensen, H., & Harvey, S. B. (2017). eHealth interventions for the prevention of depression and anxiety in the general population: A systematic review and meta-analysis. BMC Psychiatry, 17(1), 310. https://doi.org/10.1186/s12888-017-1473-1 Ferrari, M., Allan, S., Arnold, C., Eleftheriadis, D., Alvarez-Jimenez, M., Gumley, A., & Gleeson, J. F. (2022). Digital Interventions for Psychological Well-being in University Students: Systematic Review and Meta-analysis. Journal of Medical Internet Research, 24(9), e39686. https://doi.org/10.2196/39686 Heber, E., Ebert, D. D., Lehr, D., Cuijpers, P., Berking, M., Nobis, S., & Riper, H. (2017). The Benefit of Web- and Computer-Based Interventions for Stress: A Systematic Review and Meta-Analysis. Journal of Medical Internet Research, 19(2), e5774. https://doi.org/10.2196/jmir.5774 The Institute for Health Metrics and Evaluation, 2023.https://www.healthdata.org/ Ioannidis, J. (2017). Next-generation systematic reviews: Prospective meta-analysis, individual-level data, networks and umbrella reviews. British Journal of Sports Medicine, 51(20), 1456–1458. https://doi.org/10.1136/bjsports-2017-097621 Leichsenring, F., Steinert, C., Rabung, S., & Ioannidis, J. P. A. (2022). The efficacy of psychotherapies and pharmacotherapies for mental disorders in adults: An umbrella review and meta-analytic evaluation of recent meta-analyses. World Psychiatry, 21(1), 133–145. https://doi.org/10.1002/wps.20941 Reins, J. A., Buntrock, C., Zimmermann, J., Grund, S., Harrer, M., Lehr, D., Baumeister, H., Weisel, K., Domhardt, M., Imamura, K., Kawakami, N., Spek, V., Nobis, S., Snoek, F., Cuijpers, P., Klein, J. P., Moritz, S., & Ebert, D. D. (2021). Efficacy and Moderators of Internet-Based Interventions in Adults with Subthreshold Depression: An Individual Participant Data Meta-Analysis of Randomized Controlled Trials. Psychotherapy and Psychosomatics, 90(2), 94–106. https://doi.org/10.1159/000507819 Riper, H., Hoogendoorn, A., Cuijpers, P., Karyotaki, E., Boumparis, N., Mira, A., Andersson, G., Berman, A. H., Bertholet, N., Bischof, G., Blankers, M., Boon, B., Boß, L., Brendryen, H., Cunningham, J., Ebert, D., Hansen, A., Hester, R., Khadjesari, Z., … Smit, J. H. (2018). Effectiveness and treatment moderators of internet interventions for adult problem drinking: An individual patient data meta-analysis of 19 randomised controlled trials. 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