Rapidly changing peri-urban areas have great ecological and human land-use diversity. Contrasting habitats abound. However, little is known about the way that the biodiversity of a whole urban area depends on the variety of habitats and the linkages, migration and dispersal patterns between them. Great opportunities exist for extending these concepts in both the rapidly expanding manufacturing and commercial cities of Latin America and Asia and into some of the poorest peri-urban environments. To take these opportunities requires understanding of the diverse pressures on peri-urban ecosystems and their consequences for both ecosystem and human health. For some people, peri-urban areas are healthy and the scene of good living standards; for others, they offer a survival opportunity. The complex ecology of urban and peri-urban areas is constantly being disrupted locally by the injection of new species or new types and concentration of chemicals into specific habitats through human activity. Each change alters ecosystem health. The ecosystem health and human mental and physical health consequences of the interplay between economy, society, land and ecosystems in peri-urban areas provide a wonderful opportunity for innovative thinking in applied science, particularly for public health medicine, geography and human ecology.