INFANT care practices are deeply rooted in culture and represent the end results of generations of experience and conviction. It is understandable that few systematic studies of specific aspects of infant care have been undertaken; for each practice (whether feeding, fondling, toileting, etc.) is characterized by a complex process of interaction and methods of evaluation are difficult to define. Yet with progress in the study of physiologic, psychologic, and socio-cultural processes, it should become possible to study the physiologic and developmental consequences of specific infant care practices. The objective of this report is to present the results of our efforts to study one infant care practice—that of swaddling. Interest in this practice grew out of our long-term studies of the development of autonomic nervous system function in infancy. These studies of swaddling and early neurophysiologic capacity complement each other in many ways, as will be shown later. An earlier study of motor restraint by means of swaddling was designed primarily to observe the relationships between autonomic and musculo-skeletal reactivity to stimulation. As the experiment progressed, however, it appeared clear that the process of restraining the infant, per se, often produced a tranquil, "co-operative" state which greatly facilitated the studies of physiologic reactivity. As it became increasingly apparent that pacification was produced in most newborn infants, we considered with heightened curiosity what implications these findings held for clinical pediatrics and, more broadly, for evaluating the cultural practice of infant bundling or swaddling. We began to wonder whether there was not some more pervasive reason for this previously ubiquitous infant care practice, apart from the common anthropologic interpretations which will be described later in this paper.