The Commission on Macroeconomics and Health (CMH) was established by World Health Organization Director-General Gro Harlem Brundtland in January 2000 to assess the place of health in global economic development. Although health is widely understood to be both a central goal and an important outcome of development, the importance of investing in health to promote economic development and poverty reduction has been much less appreciated. We have found that extending the coverage of crucial health services, including a relatively small number of specific interventions, to the world’s poor could save millions of lives each year, reduce poverty, spur economic development, and promote global security.