A meticulously designed, detailed study presents one aspect of extensive research in early interactional experience, focusing upon the initial phase of infant-caretaker interaction. The conceptual model is of mother-infant as components in an interactional field-adaptive process leading to ever developing synchronous organization within and between the component parts. The critical first phase accomplishment is the establishment of synchronization between intrinsic infant rhythms and stable regularities of the caretaker. Psychoanalysts interested in experimental research design will find this paper rewarding.