I propose to assess in human infants the development of affective systems that may be opioid-mediated. Specific Aim 1 capitalizes on our discovering a remarkable calming effect of intraoral sucrose in newborn infants and is guided by a substantial animal literature that shows interactions between sucrose and pain systems that are opioid-mediated will determine: (a) the effects of sucrose, other sugars, and milk on responses. Preliminary evidence in human infants during circumcision demonstrates a diminution of pain by glucose and sucrose. (b) Calming sucrose in infants of morphine or heroin addicted mothers who are opio tolerant. (c) The Calming effects of sugar on pain experienced by in during routine medical treatment will be compared with the effects of contact comfort provided by the mother. Based on the animal literatur separation between sucrose mediated and contact mediated calming is predicted.