As populations throughout the world live longer, there is an increasing trend toward global commonality of health concerns. This trend mirrors a growing demand for health and access to new interventions to prevent, diagnose, and treat disease. The knowledge base required to meet these needs is not only of a technical kind, deriving from experiments of researchers, but must also draw from the experiences of governments in allocating resources effectively and efficiently to improve human health. This report from the Board on International Health of the Institute of Medicine focuses on the interest of the United States in these global health transitions. The report argues that America has a vital and direct stake in the health of people around the globe, and that this interest derives from both America’s long and enduring tradition of humanitarian concern and compelling reasons of enlightened self-interest.