It is estimated that 80% of the world's population will live in cities by 2050. In recent decades, however, this rapid urbanization has provoked or worsened many social and ecological problems throughout the world. So it is worth asking whether current models of urban development can be improved. By taking a close look at the specific needs of slum dwellers in South Africa, by developing a basis of organic farming in Cuba, and by creating eco-neighbourhoods in China, some social entrepreneurs have been able to transform the urban landscape.