This study examined the effect of a modification of nursing care on stressors associated with care procedures for low birth weight infants in a neonatal intensive care unit (NICU); and on infants' physiological, motor, and behavioral development. The nursing staff of an NICU received training to reduce environmental and procedural stress, support motor development, and support organization of infants' patterns of sleep and wakefulness. A control group of 21 infants who weighed less than 1,501 grams at birth was cared for before the training, and an experimental group of 24 similar weight infants was cared for after the training. The range of infants' gestational ages at birth was 26 to 33 weeks, and at discharge from the hospital, 33 to 56 weeks. The study data are presented for 30, 32, and 34 weeks. Results indicated that blood oxygen levels at 30 and 34 weeks were higher for experimental than control infants. Experimental infants exhibited less jerky movement at 30 and 32 weeks, and more flexor movement at all ages, than did control infants. Experimental infants spent more time in the alert wakeful state at 34 weeks than did control infants. A list of 42 references is provided. (BC)