At the Second European Conference on Environment and Health held in Helsinki in June 1994, urban health was attributed a high priority. This decision by the Ministers of Environment and Health from European countries reflects and reinforces a growing worldwide concern in the 1990s about the health status of residents of urban areas in all continents. The reasons for this concern include the rapid rate of urbanization and the increasing number of environmental, economic, and social problems, which have a negative impact on health and well-being in cities. This review presents a theoretical and methodological framework for the study of this vast and complex subject area. The paper proposes and illustrates an ecological perspective by discussing housing conditions and homelessness, as well as the concentration of poverty and deprivation in precise neighborhoods. To promote health and well-being more effectively, the ecological perspective presented in this paper can be applied by public health officers, by urban planners, and by policy decision-makers at national and local levels to promote our understanding of the multi-dimensional nature of health disorders of citizens. This approach should be a high priority for the beginning of the 21st century.