BACKGROUND: Many reviews with conflicting findings on dementia caregiver interventions have been published. A meta-review was conducted to synthesize the findings of systematic reviews and meta-analyses. METHODS: MEDLINE, PsycINFO, CINAHL and Cochrane Library were searched to identify reviews published during 2006-2018. RESULTS: Sixty reviews covering > 500 intervention studies were selected and appraised with Assessment of Multiple Systematic Reviews (AMSTAR) II. The great majority of studies were of low quality according to AMSTAR II, but quality factors appeared unrelated to the conclusions obtained. Depression was most modifiable, with effects found across a spectrum of interventions (psychoeducation, counseling/psychotherapy, occupational therapy, mindfulness-based interventions, multicomponent interventions, etc.). Evidence of intervention effect was also found for quality of life (psychoeducation), mastery (psychoeducation, occupational therapy and multicomponent interventions) and communication skills (communication training). Null or weak results were found for anxiety, social support and burden. Support groups and respite were generally ineffective. There was no evidence that dyadic programs were better than caregiver-only programs, or that programs delivered individually or in groups would differ in their impacts. The evidence also does not support multicomponent interventions to have broader impacts than single-component programs. Methodological issues in the existing reviews (e.g., selective use of studies to serve different research purposes and inconsistent classification of interventions) were noted and taken into account when interpreting findings. CONCLUSIONS: This meta-review clarified variations in review methodology and identified a few potent groups of intervention (most notably psychoeducation, psychotherapy, occupational therapy, and multicomponent interventions), although no intervention type had broad effects on caregiver outcomes. We note that improvements are needed in the reporting of intervention studies and in making the classification of interventions more transparent and consistent. We further recommend fewer and larger-scale reviews and more attention to positive outcomes in order to better inform the field. Developing interventions with broader impacts and packaging them to meet caregivers' changing needs in the course of dementia should be a priority for researchers and practitioners.