We studied preterm infants to determine whether they have more difficult temperaments than term infants, and whether temperament is related to perinatal factors and to later performance on infants tests. Parents of 98 preterm and 89 full-term infants completed the Toddler Temperament Scale (TTS) when their children were 12 months post-term. Ninety-five of the 98 preterm infants also received the Bayley Scales of infant Development and were diagnosed as to the presence and severity of cerebral palsy (CP) at one year post-term. Preterm and full-term infants did not differ significantly on overall temperament type or on any of nine temperament dimensions. Degree of respiratory distress was correlated significantly with premature infants' receiving scores significantly different from normal on some temperament dimensions. Poorer performance on the Bayley Mental Scales was significantly associated with temperament characteristics of lower adaptability, lower persistence, and more withdrawal from new stimulation.