Global health today is characterized by a mix of promising developments and troubling trends. Life expectancy is on the rise, and maternal and child mortality rates are falling. But millions lack basic nutrition, primary health care, and access to vaccinations; we are ill-prepared for the next global pandemic; tobacco use kills six million people annually; and noncommunicable diseases, such as diabetes and cardiovascular disease, have emerged as leading killers. Nations with differing levels of resources are cooperating in new ways and discovering that learning happens in all directions as they do. But the world’s refugee crisis has become a health emergency, and climate change is threatening global stability. Here’s an overview of the opportunities and threats we face.