The concept of pain in infancy was explored. It was suggested that our every day usage of the term pain be applied to infants. Essentially this suggestion is that we infer that an infant has a subjective experience that is unpleasant when there is evidence of tissue damage and the infant responds with signs of distress, such as crying, increased heart rate, facial expression consistent with distress or other signs. Conceptualizations of adult clinical pain and infant emotions were compared. It was proposed that our concept of infant pain should be multivariate and should include the ecological context in which pain occurs. In section 2 methodological issues were discussed. Ethical concerns for the protection of infant rights were voiced. Numerous opportunities for studying infant pain produced by necessary medical procedures were pointed out. A number of response systems which offer promise in understanding infant pain were reviewed with respect to their proven applicability to infant emotional and cognitive processes or to adult pain processes. This paper attempted to organize information which will be helpful to the researcher interested in infant pain or developmental processes in pain. From the preceding it should be obvious how remarkably little data we have which bears directly on the issue. The close association between the study of pain and the study of emotion has been shown. The study of emotional development, while ahead of the study of developmental aspects of pain, still lags far behind the study of cognitive development. Recently there has been a call for increased study of the development of emotion. The study of the development of pain might well proceed hand in hand. The present state of the field of infant pain is such that almost any data will add to our knowledge base. The complexity of the concept and the wide range of response systems would suggest that multidisciplinary research teams may develop some of the best research efforts. A multidisciplinary approach has been found to be essential in the treatment of chronic pain, for example. A listing of some of the types of professionals who would contribute would include: physicians, nurses, psychologists, biologists (including those trained in neurophysiology, ethology and endocrinology), sociologists and anthropologists. University medical centers seem an ideal environment for conducting such research, given the close proximity of various specialists and an available subject population.