The urge to perform medical service abroad has always been present at some level among U.S. physicians. In the early years, this often took the form of missionary work. The growth of nongovernmental organizations (NGOs) in the twentieth century provided the vehicle for many others. In recent years, the number of voluntary organizations sponsoring people participating in health in the developing world has proliferated, and the U.S. government itself—through the Centers for Disease Control and Prevention (CDC), U.S. Agency for International Development (USAID)–sponsored programs, and even the military—has provided physicians, nurses, and public health experts for service in the developing world. The magnitude of this “mission” is hard to measure. Johns Hopkins professor Timothy Baker published an estimate in 1987, putting the figure at something less than one-third of 1 percent of U.S. physicians at that time—a victory or an embarrassment, depending on one’s expectations. Today the numbers are surely higher, although quantification remains a challenge, since the length of service, clinical focus, and sponsoring organizations are so numerous and variable. There can be no question, however, that interest in global health among young Americans in the health sciences is on the rise. A recent survey of U.S. medical students concluded that 20 percent had gone abroad (largely to the developed world) during medical school, as compared with only 4 percent in the 1980s. A Pediatric AIDS Corps, sending physicians to Africa, sponsored by the Baylor College of Medicine and the Bristol-MyersSquibb Foundation, recently tried to recruit fifty physicians. They were overwhelmed by applications from superbly trained young pediatricians and family physicians. But working abroad is not a simple matter. The organizations, countries, clinical needs, obstacles, hazards, and potential for mismatches are many. Once abroad, the U.S. health professional will be working amid a welter of national and international programs, initiatives, and campaigns. A baseline set of questions for anyone considering health work in the developing world should be asked and answered before departure. Edward O’Neil Jr., a U.S.-trained emergency medicine physician, has devoted his young career to exploring and answering many of these questions. He is the founder and president of Omni Med, an organization that tracks medical service opportunities and supports service/teaching programs in four developing countries (Belize, Guyana, Kenya, and Thailand, as of April 2007). O’Neil has published two enormously useful volumes on the subject. The first, Awakening Hippocrates, is a superb introduction to the subject of international