The effects of perinatal risk and gestational age on sensory responsiveness and the ability to habituate were evaluated in three groups of preterm newborns designated as at high-, moderate-, and low-risk for developmental disability. Two major hypotheses were investigated: 1) that preterm infants have an elevated sensory threshold leaving them relatively unavailable to stimulation and 2) that once the preterm is stimulated sufficiently to respond, he/she is largely unable to habituate to repeated stimulus presentations. Additionally, the reliability of responsiveness and habituation over a 24-hour period was assessed.