Abstract Globally and locally, ongoing demographic, socio-cultural and economic changes have implications for unpaid carers. For those who provide unpaid care, particularly at higher intensities, there is substantial evidence of negative effects on employment, health and wellbeing, with associated individual and soci-etal costs. For these reasons, there is increasing policy emphasis on supporting unpaid care in the UK, mirrored, and in some cases exceeded, internationally. This paper aims to provide an overview of the interna-tional evidence on effective support for unpaid carers. This evidence synthesis finds an extensive literature on a wide range of potentially effective interventions to support unpaid carers under the broad categories of indirect support (services for the care-recipient), direct support (such as psychological therapies), work condi-tions, and combinations of these. However, there are significant gaps in the evidence base with regards to interventions, outcomes and types of caring situation studied, with a dearth of evidence on cost-effectiveness and few evaluations of key recent policy initiatives. Evidence is strongest and most consistent for formal care services for people with care needs (so-called ‘replacement’ or ‘substitution’ care); flexible working conditions; psychological therapy, training and educa-tion interventions; and support groups. In many cases it may be that a combination of interventions is most effective. These findings have implications for social care policy and practice which aims to support carers, particularly in the context of the changing landscape of global macro-level processes and recent policy, legislative and funding changes for local authority and voluntary sector providers of support and services for carers in the UK.Keywords: unpaid care, support for unpaid carers, social care services, work conditions, cash benefits, review.