Prompted by the 20th anniversary of the 1993 World Development Report, a Lancet Commission revisited the case for investment in health and developed a new investment framework to achieve dramatic health gains by 2035. The Commission's report has four key messages, each accompanied by opportunities for action by national governments of low-income and middle-income countries and by the international community. First, there is an enormous economic payoff from investing in health. The impressive returns make a strong case for both increased domestic financing of health and for allocating a higher proportion of official development assistance to development of health. Second, modeling by the Commission found that a "grand convergence" in health is achievable by 2035-that is, a reduction in infectious, maternal, and child mortality down to universally low levels. Convergence would require aggressive scale up of existing and new health tools, and it could mostly be financed from the expected economic growth of low- and middle-income countries. The international community can best support convergence by funding the development and delivery of new health technologies and by curbing antibiotic resistance. Third, fiscal policies -such as taxation of tobacco and alcohol- are a powerful and underused lever that governments can use to curb non-communicable diseases and injuries while also raising revenue for health. International action on NCDs and injuries should focus on providing technical assistance on fiscal policies, regional cooperation on tobacco, and funding policy and implementation research on scaling-up of interventions to tackle these conditions. Fourth, progressive universalism, a pathway to universal health coverage (UHC) that includes the poor from the outset, is an efficient way to achieve health and financial risk protection. For national governments, progressive universalism would yield high health gains per dollar spent and poor people would gain the most in terms of health and financial protection. The international community can best support countries to implement progressive UHC by financing policy and implementation research, such as on the mechanics of designing and implementing evolution of the benefits package as the resource envelope for public finance grows.