The concept of “Ecology” has experienced some notable mutaions, since it was introduced by Ernest Haeckel, the German biologist, in 1869. This paper outlines its growth as a social concept and discusses ways in which an ecological approach can illuminate the study of urban education in the nineteenth century. The first section surveys the development of ecologial principles from their prototypical and still implicit use in the empirical social surveys of the nineteenth century, through their more formal attachment to a theory of urban society in the 1920s, as far as the 1970s when, despite all the vicissitudes faced over the previous half-century, they continued to be accepted as somewhat valid in the explanation of urban society.