FROM ITS BEGINNING the field of public health has been concerned with man in relation to his environment and, in this sense, oriented toward concepts which were later subsumed under the terms ecology and human ecology. Today, interest in the reciprocal relationships between man and his environment has greatly broadened and intensified. Clearly, the solution of many emerging health problems will require greater knowledge of the balances and interactions involved. It is ;clear also that we must understand these relationships in their totality even though we may be obliged to dissect them separately. Sooner or later, we must somehow contrive to assemble them as a wholethe physical, the biological, and the social. If such an endeavor falls within the province of any single field, it would seem to be that of human ecology. Accordingly, it is the purpose of this paper to explore some of the ways in which human ecology, as a system of thought, and public health, as a field of application, may be associated profitably.