This independent report was commissioned by Public Health Wales to explore the economic evidence relevant to investment in older people living in Wales. As health economists, we focus on evidence of the costs to the public sector and wider society of economic issues, and evidence of the cost-effectiveness or return on investment of evidence-based interventions to address them. This report brings together robust international and UK evidence on the relative cost-effectiveness and return on investment of devoting public sector resources to programmes and practices supporting older people. Where possible, we have translated evidence of potential savings from these interventions to a current Wales context through currency conversion, inflation and scaling of figures (see rapid review methodology and analysis section below). Our intended audience includes Public Health bodies and other agencies in Wales, England, Scotland and Northern Ireland; the seven Health Boards across Wales; Welsh local government and the third sector, who currently and potentially have a role in supporting and benefiting from older people living across Wales.