Health care costs are rising far faster than GDP growth. This has been an unrelenting problem across affluent countries. Together these rising costs, limitations in medical care equity, and inadequate attention to social determinants of health are already increasing disparities in health outcomes. Turning the current situation around will require innovative social policies and public health measures that more efficiently and effectively prevent illnesses and injuries, as well as health care provision and financing systems that more efficiently and effectively treat them. Important insights can be gained from a rigorous examination of which past efforts have failed and which have succeeded in leading economies around the world. This five-year initiative will enable us to map the biggest problem areas and greatest successes in the world's leading economies, as well as to rigorously examine and systematically learn from the differences among countries in terms of which are performing well and which are struggling.