The upsurge of urbanization, often poorly planned and uncontrolled, has caused major impacts on human societies for at least two centuries. Urban environments and urbanized lifestyles have strong influences on health and well-being, including on infant and childhood populations in developed and underdeveloped countries, as well as among societies in developmental and environmental transition around the world. Urbanization will inevitably have significant impacts on the health of future generations. Notably, the health consequences of urbanized lifestyles are not confined to residents of cities and large towns but rather are becoming manifest in rapidly changing, previously traditional societies in rural and remote areas because globalization is altering infant feeding practices and the dietary habits and lifestyle patterns of their children. In underdeveloped countries, overcrowding and environmental pollution are huge problems that are exacerbated by undernutrition and infection, particularly respiratory and diarrheal diseases. In developed societies, other problems like injuries; poisonings; violence; drug abuse; exposure to chemical, biological, industrial, and atmospheric pollutants, including pesticides; sexually transmissible diseases; and 'lifestyle' diseases, including obesity and cardiovascular disease risk, are of great current and potential importance.