AbstractThere is a growing database of research on self-help and Internet-guided interventions in the treatment of common mental disorders, and a number of meta-analyses have now been published. This article provides a systematic review of meta-analyses on the efficacy of self-help interventions, including Internet-guided therapy, for depression and anxiety disorders. Searches were conducted in PubMed, PsychINFO, EMBASE, and the Cochrane database for statistical meta-analyses of randomized, controlled trials of self-help or Internet-guided interventions for depression or anxiety disorders published in English. Reference lists were also used to find additional studies. Effect sizes were tabulated; 13 meta-analyses reported medium to large effect sizes for self-help interventions. Studies included in the meta-analyses differed in samples, type of self-help (eg, computer-aided, Internet-guided), control conditions, and study design. The meta-analyses indicate that self-help methods are effective in a range of different disorders, including depression and anxiety disorders. Most meta-analyses found relatively large effect sizes for self-help treatments, independent of the type of self-help, and comparable to effect sizes for face-to-face treatments. However, further research is needed to optimize the use of self-help methods.