This article explores global health and the way in which the whole world is increasingly interdependent in terms of health. High-income countries need to help redress the balance of power and resources around the world, for self interest and self preservation if for no other reason. These countries have a particular responsibility to help support the training of more health workers and to strengthen health systems in low-income and middle-income countries. In this interdependent world, high-income countries can learn a great deal from poorer ones as well as vice versa, and concepts of mutuality and codevelopment will become increasingly important.