Background : During the 2020 COVID-19 pandemic, millions of older adults are advised to avoid contact with those outside their household. ‘Social distancing’ has highlighted the need to minimise loneliness and isolation through the provision of remotely delivered befriending, social support and low intensity psychosocial interventions. We wanted to know what interventions are effective and how they work to help inform decisions about different approaches. Methods : We followed a systematic ‘review of reviews’ approach and included systematic reviews focussed on the effectiveness or implementation of remote interventions to reduce levels of social isolation or loneliness in adults aged 50+. Searches of 11 databases were undertaken during April 2020 and eligible reviews were critically appraised using AMSTAR2. Narrative synthesis was used at a review and study level to develop a typology of intervention types and their effectiveness. Intervention Component Analysis (ICA) and Qualitative Comparative Analysis (QCA) were used at a study level to explore the characteristics of successful interventions. Results : We synthesised evidence from five systematic reviews and 18 primary studies. Remote befriending, social support and low intensity psychosocial interventions took the form of: (i) supported video-communication; (ii) online discussion groups and forums; (iii) telephone befriending; (iv) social networking sites; and (v) multi-tool interventions. The majority of studies utilised the first two approaches, and were generally regarded positively by older adults, although with mixed quantitative evidence around effectiveness. Focussing on processes and mechanisms, using ICA and QCA, we found that the interventions that were most effective in improving social support: (i) enabled participants to speak freely and to form close relationships; (ii) ensured participants have shared experiences/characteristics; (iii) included some form of pastoral guidance. Conclusions : The findings highlight a set of intervention processes that should be incorporated into interventions, although they do not lead us to recommend particular modes of remote support.