Abstract: New concepts in infant development of capabilities for social response are examined in a publication of a pediatrics round table series for child health care professionals and parents. Since understanding one's baby is necessary to successful parenting, insights into the infant's sensitivity and response to its new world during the first year of life are presented. The infant is seen as a partner in a mother-child system. Section I describes infant rhythms and responses in terms of preparation for that partnership. Section II proposes developmental models which view the infant as a social being. Section III reviews the ontogeny of the mother-infant relationship. The human infant has a long and dependent relationship with those that give it its care. These new perspectives consider the infant as being well prepared for interaction with its environment and the people in it.