Rhythmic stimulation will be provided as an intervention for premature infants with the aim of preventing or reducing mental and emotional disability. The intervention is unique in two major ways: 1) stimulation is optional for the infant--the infant regulates the amount and temporal distribution of stimulation received; and 2) the rhythm is set for each infant, to match a biological rhythm of the infant, or of the mother. Two premises are basic for this intervention: 1) that premature infants are deprived of the organizing forces of the mother's biological rhythms provided in utero, and 2) that self-reflecting rhythms will be attractive to the infant. The source of stimulation is a specially constructed "breathing" bear placed in the crib with the infant. The Bear breathes by means of a pump placed outside the crib. The results of a study indicate that premature infants are capable of seeking contact with a Breathing Bear, breathing at the rate of the infant during Quiet Sleep. This experience led to increased Quiet Sleep, indicating effective entrainment and facilitation of CNS maturation in these infants. Using continuous time-lapse video recording, measures of contact with the bear, Quiet Sleep, and activity level were obtained. The subjects were stable prematures of 32 weeks G.A. The first study will replicate the one just described, to permit longitudinal assessment of effects of the pre-term intervention (12 subjects in each of 3 groups). The next study will explore the infants' preferred rate of breathing for the bear: the infant's own respiration rate in Quiet Sleep, or in Active Sleep, or the mother's respiration or heart rate (12 infants in each of the 4 groups). The third study will compare infants' preferences for the Breathing Bear and another source of rhythmic stimulation, an oscillating air mattress pad (12 subjects in each of the 2 groups). The bear, breathing to match the infant's own rate during Quiet Sleep, is expected to be the most preferred and most effective intervention. Effects will be assessed at 3 age periods: 1) during the intervention, using measures of Quiet Sleep and activity; weight gain; and the Korner Maturity Scales; 2) at 2-5 weeks post-term, using measures of state stability from home monitoring; and 3) home observations of mother-infant interaction at 1 year, and Bayley Mental and Motor Scales at 1 and 2 years. We expect the self-selected, self-reflecting stimulation to have lasting facilitative effects on the emotional and intellectual functioning of the premature infants.