‘Investing to Save Lives’ make a compelling case for strategic investment in preventative road safety measures. The case studies, developed by Social Finance UK and Impact Strategist, are drawn from road safety programs in Australia and Cambodia. They detail astronomical health costs resulting from road trauma in high income countries, the hidden costs borne by families in low income countries with limited access to health services, insurance protection or welfare, and the immediate and long term human and financial benefits of front-loading investment in comprehensive road safety interventions.