We investigated the effects of a year-long home intervention with a sample of preterm infants randomly assigned to 1 of 3 groups: a developmental intervention, a parent-infant intervention, and a no-treatment control group. A full-term no-treatment control was also used. Both intervention approaches focused on the parent-child unit, providing training for parents to improve observational skills, emotional support, and information about community resources. However, whereas specific tasks to facilitate the child's development were provided in the developmental intervention group, the quality of the parent-infant interaction was the target for treatment in the other group. All infants were assessed at 4, 8, 12, and 16 months of age corrected for prematurity. The results suggest that although both intervention approaches were effective in modifying some aspects of the home environment and, to a lesser degree, in improving infants' cognitive development, the parent-infant interaction approach seemed to have the greater impact. These findings confirm previous observations regarding the cognitive development of preterm and full-term infants during the first 18 months of life and demonstrate changes in behavior and behavior styles in both pre- and full-term infants as they become older.