Healthy neonates (48) born to multiparae were randomly assigned to view a moving stimulus either in the horizontal or the upright position, with or without added vestibular stimulation and with or without pacifer sucking. The infant was shown a moving black line inside a strictly controlled visual environment provided by an apparatus which permitted horizontal and upright positioning and displacement of the infant. Visual tracking was recorded by a concealed TV [television] camera positioned at a constant distance and angle from the infants'' eyes in both positions. Quality of tracking during each of 4 trials was scored on a 7-point scale. Vestibular-proprioceptive stimulation provided to the infant horizontally or semivertically seemed to significantly enhance his visual tracking, whereas the upright position did not. Pacifer sucking also improved his performance.