This paper outlines an ethological study of the development of infant feeding. Firstly, a framework for analysing the practice of infant feeding is presented from which five sources of faulty feeding and possible infant obesity are identified. Then there is a discussion of the research design which attempts to disentangle the various contributions of environmental, developmental and constitutional factors. This focuses on the infant's feeding behaviour and mother–infant interaction during feeding, and the appropriate observational methods developed by ethologists are described. Finally data from a part of the study concerned with early food regulation and the mother's concept of feeding are presented. It appears that at 3 days of age bottle fed babies are having more to eat than breast fed babies, that mothers are muddled about demand feeding and that mothers who are breast feeding are probably overemphasizing the psychological aspects of the feeding environment.