Multiple developmental assessments were made at 4-month intervals over the first year of life for 2 groups of infants born at risk and 1 normal group. The groups included 46 preterm respiratory distress syndrome infants, 46 postterm postmaturity syndrome, and 59 term normal infants. The mothers were white, multiparous, middle-class, high school graduates averaging 25 years of age. Analyses of group differences revealed that the preterm respiratory distress syndrome (RDS) infants continued to exhibit delays in motor and mental development and the postmature infants in mental development. Discriminant function analyses suggesting that the most efficient predictors and accurate discriminators of continuing risk were as follows: the Parmelee obstetric and postnatal complications scores and the Brazelton interactive and motoric process scores at birth; the Denver rating, mother-infant interaction and Carey temperament ratings at 4 months; and the Bayley mental and motor scores at 8 months. On the basis of their weighted assessment scores, infants were assigned a cumulative risk index at each assessment period.